Initial changes for PriceWelcomeMessageCard component

This change adds a new message type PRICE_WELCOME to current message
scheme. A new layout tab_grid_price_message_card_item.xml is created
and a new UiType PRICE_MESSAGE is added correspondingly.
This feature is hidden behind the flag ENABLE_PRICE_TRACKING.
Some more specific logics such as where to show the message card
will be added in the later CLs, as well as the tests for this CL.

Bug: 1148020
Change-Id: If4d6b11762c9a16f6d73ee05bcee7f6bacfdcbf0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2556657
Commit-Queue: Zhiyuan Cai <zhiyuancai@google.com>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Reviewed-by: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834477}

chrome/android/features/tab_ui/BUILD.gn

@@ -64,6 +64,7 @@ android_resources("java_resources") {
     "java/res/layout/iph_drag_and_drop_dialog_layout.xml",
     "java/res/layout/new_tab_tile_card_item.xml",
     "java/res/layout/price_card.xml",
+    "java/res/layout/price_welcome_message_card_item.xml",
     "java/res/layout/selectable_tab_grid_card_item.xml",
     "java/res/layout/selectable_tab_list_card_item.xml",
     "java/res/layout/single_tab_view_layout.xml",
@@ -123,6 +124,10 @@ android_library("java") {
     "java/src/org/chromium/chrome/browser/tasks/tab_management/NewTabTileViewBinder.java",
     "java/src/org/chromium/chrome/browser/tasks/tab_management/NewTabTileViewProperties.java",
     "java/src/org/chromium/chrome/browser/tasks/tab_management/PriceCardView.java",
+    "java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardView.java",
+    "java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardViewBinder.java",
+    "java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardViewModel.java",
+    "java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageService.java",
     "java/src/org/chromium/chrome/browser/tasks/tab_management/SelectableTabGridView.java",
     "java/src/org/chromium/chrome/browser/tasks/tab_management/TabGridDialogCoordinator.java",
     "java/src/org/chromium/chrome/browser/tasks/tab_management/TabGridDialogMediator.java",

chrome/android/features/tab_ui/java/res/layout/price_welcome_message_card_item.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2020 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+<org.chromium.chrome.browser.tasks.tab_management.PriceWelcomeMessageCardView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/tab_grid_price_welcome_message_item"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="@drawable/message_card_background_with_inset">
+    <LinearLayout
+        android:id="@+id/card_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_gravity="center"
+        android:orientation="vertical">
+        <org.chromium.chrome.browser.tasks.tab_management.PriceCardView
+            android:id="@+id/price_info_box"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:gravity="center_horizontal"
+            android:layout_gravity="center"
+            android:layout_marginTop="16dp"
+            android:layout_marginBottom="16dp"/>
+        <TextView
+            android:id="@+id/title"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="4dp"
+            android:layout_gravity="center_horizontal"
+            android:textAppearance="@style/TextAppearance.TextLarge.Primary"
+            android:gravity="center_horizontal" />
+        <TextView
+            android:id="@+id/content"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_horizontal"
+            android:gravity="center_horizontal"
+            android:textAppearance="@style/TextAppearance.TextMedium.Secondary"
+            android:layout_marginStart ="24dp"
+            android:layout_marginEnd="24dp" />
+        <org.chromium.ui.widget.ButtonCompat
+            android:id="@+id/action_button"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            style="@style/FilledButton.Flat"
+            android:layout_gravity="center"
+            android:layout_marginTop="16dp"
+            android:layout_marginBottom="16dp"
+            android:layout_marginStart ="24dp"
+            android:layout_marginEnd="24dp"
+            android:paddingTop="8dp"
+            android:paddingBottom="8dp" />
+    </LinearLayout>
+    <org.chromium.ui.widget.ChromeImageView
+        android:id="@+id/close_button"
+        android:layout_width="24dp"
+        android:layout_height="24dp"
+        android:contentDescription="@string/close"
+        android:layout_gravity="end"
+        android:layout_marginTop="16dp"
+        android:layout_marginEnd="16dp"
+        android:tint="@color/default_icon_color"/>
+</org.chromium.chrome.browser.tasks.tab_management.PriceWelcomeMessageCardView>

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/MessageCardProviderMediator.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.tasks.tab_management;
 
 import static org.chromium.chrome.browser.tasks.tab_management.MessageService.MessageType.IPH;
+import static org.chromium.chrome.browser.tasks.tab_management.MessageService.MessageType.PRICE_WELCOME;
 import static org.chromium.chrome.browser.tasks.tab_management.MessageService.MessageType.TAB_SUGGESTION;
 
 import android.content.Context;
@@ -103,6 +104,11 @@ public class MessageCardProviderMediator implements MessageService.MessageObserv
                 assert data instanceof IphMessageService.IphMessageData;
                 return IphMessageCardViewModel.create(mContext, this::invalidateShownMessage,
                         (IphMessageService.IphMessageData) data);
+            case PRICE_WELCOME:
+                assert data instanceof PriceWelcomeMessageService.PriceWelcomeMessageData;
+                return PriceWelcomeMessageCardViewModel.create(mContext,
+                        this::invalidateShownMessage,
+                        (PriceWelcomeMessageService.PriceWelcomeMessageData) data);
             default:
                 return new PropertyModel.Builder(MessageCardViewProperties.ALL_KEYS)
                         .with(MessageCardViewProperties.IS_INCOGNITO, false)

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/MessageCardViewProperties.java

@@ -7,6 +7,7 @@ package org.chromium.chrome.browser.tasks.tab_management;
 import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.CARD_ALPHA;
 import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.CARD_TYPE;
 
+import org.chromium.chrome.browser.tab.state.ShoppingPersistedTabData;
 import org.chromium.ui.modelutil.PropertyKey;
 import org.chromium.ui.modelutil.PropertyModel;
 
@@ -46,10 +47,16 @@ class MessageCardViewProperties {
             new PropertyModel.WritableBooleanPropertyKey();
     public static final PropertyModel.WritableBooleanPropertyKey IS_INCOGNITO =
             new PropertyModel.WritableBooleanPropertyKey();
+    public static final PropertyModel.WritableObjectPropertyKey<String> TITLE_TEXT =
+            new PropertyModel.WritableObjectPropertyKey<>();
+    public static final PropertyModel
+            .WritableObjectPropertyKey<ShoppingPersistedTabData.PriceDrop> PRICE_DROP =
+            new PropertyModel.WritableObjectPropertyKey<>();
 
-    public static final PropertyKey[] ALL_KEYS = new PropertyKey[] {ACTION_TEXT, DESCRIPTION_TEXT,
-            DESCRIPTION_TEXT_TEMPLATE, MESSAGE_TYPE, ICON_PROVIDER, UI_ACTION_PROVIDER,
-            UI_DISMISS_ACTION_PROVIDER, MESSAGE_SERVICE_ACTION_PROVIDER,
-            MESSAGE_SERVICE_DISMISS_ACTION_PROVIDER, DISMISS_BUTTON_CONTENT_DESCRIPTION,
-            SHOULD_KEEP_AFTER_REVIEW, IS_ICON_VISIBLE, CARD_TYPE, CARD_ALPHA, IS_INCOGNITO};
+    public static final PropertyKey[] ALL_KEYS =
+            new PropertyKey[] {ACTION_TEXT, DESCRIPTION_TEXT, DESCRIPTION_TEXT_TEMPLATE,
+                    MESSAGE_TYPE, ICON_PROVIDER, UI_ACTION_PROVIDER, UI_DISMISS_ACTION_PROVIDER,
+                    MESSAGE_SERVICE_ACTION_PROVIDER, MESSAGE_SERVICE_DISMISS_ACTION_PROVIDER,
+                    DISMISS_BUTTON_CONTENT_DESCRIPTION, SHOULD_KEEP_AFTER_REVIEW, IS_ICON_VISIBLE,
+                    CARD_TYPE, CARD_ALPHA, IS_INCOGNITO, TITLE_TEXT, PRICE_DROP};
 }

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/MessageService.java

@@ -18,13 +18,15 @@ import java.lang.annotation.RetentionPolicy;
  * understands.
  */
 public class MessageService {
-    @IntDef({MessageType.TAB_SUGGESTION, MessageType.IPH, MessageType.ALL})
+    @IntDef({MessageType.TAB_SUGGESTION, MessageType.IPH, MessageType.PRICE_WELCOME,
+            MessageType.ALL})
     @Retention(RetentionPolicy.SOURCE)
     public @interface MessageType {
         int FOR_TESTING = 0;
         int TAB_SUGGESTION = 1;
         int IPH = 2;
-        int ALL = 3;
+        int PRICE_WELCOME = 3;
+        int ALL = 4;
     }
 
     /**

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/PriceTrackingUtilities.java

@@ -19,6 +19,8 @@ public class PriceTrackingUtilities {
     @VisibleForTesting
     public static final String TRACK_PRICES_ON_TABS =
             ChromePreferenceKeys.PRICE_TRACKING_TRACK_PRICES_ON_TABS;
+    private static final String PRICE_WELCOME_MESSAGE_CARD =
+            ChromePreferenceKeys.PRICE_TRACKING_PRICE_WELCOME_MESSAGE_CARD;
 
     @VisibleForTesting
     public static final SharedPreferencesManager SHARED_PREFERENCES_MANAGER =
@@ -40,4 +42,18 @@ public class PriceTrackingUtilities {
         return SHARED_PREFERENCES_MANAGER.readBoolean(
                 TRACK_PRICES_ON_TABS, TabUiFeatureUtilities.isPriceTrackingEnabled());
     }
+
+    /**
+     * Forbid showing the PriceWelcomeMessageCard any more.
+     */
+    public static void disablePriceWelcomeMessageCard() {
+        SHARED_PREFERENCES_MANAGER.writeBoolean(PRICE_WELCOME_MESSAGE_CARD, false);
+    }
+
+    /**
+     * @return Whether the PriceWelcomeMessageCard is disabled by users.
+     */
+    public static boolean isPriceWelcomeMessageCardDisabled() {
+        return !SHARED_PREFERENCES_MANAGER.readBoolean(PRICE_WELCOME_MESSAGE_CARD, true);
+    }
 }

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardView.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tasks.tab_management;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.util.AttributeSet;
+import android.widget.FrameLayout;
+import android.widget.TextView;
+
+import org.chromium.chrome.browser.tab.state.ShoppingPersistedTabData;
+import org.chromium.chrome.tab_ui.R;
+import org.chromium.ui.widget.ButtonCompat;
+import org.chromium.ui.widget.ChromeImageView;
+
+import java.lang.ref.WeakReference;
+
+class PriceWelcomeMessageCardView extends FrameLayout {
+    private static WeakReference<Bitmap> sCloseButtonBitmapWeakRef;
+
+    private PriceCardView mPriceInfoBox;
+    private TextView mTitle;
+    private TextView mContent;
+    private ButtonCompat mActionButton;
+    private ChromeImageView mCloseButton;
+
+    public PriceWelcomeMessageCardView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+
+        mPriceInfoBox = findViewById(R.id.price_info_box);
+        mTitle = findViewById(R.id.title);
+        mContent = findViewById(R.id.content);
+        mActionButton = findViewById(R.id.action_button);
+        mCloseButton = findViewById(R.id.close_button);
+
+        if (sCloseButtonBitmapWeakRef == null || sCloseButtonBitmapWeakRef.get() == null) {
+            int closeButtonSize =
+                    (int) getResources().getDimension(R.dimen.tab_grid_close_button_size);
+            Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.btn_close);
+            sCloseButtonBitmapWeakRef = new WeakReference<>(
+                    Bitmap.createScaledBitmap(bitmap, closeButtonSize, closeButtonSize, true));
+        }
+        mCloseButton.setImageBitmap(sCloseButtonBitmapWeakRef.get());
+    }
+
+    /**
+     * Set title text.
+     * @param titleText Text to be displayed.
+     */
+    void setTitleText(String titleText) {
+        mTitle.setText(titleText);
+    }
+
+    /**
+     * Set content text.
+     * @param contentText Text to be displayed.
+     */
+    void setContentText(String contentText) {
+        mContent.setText(contentText);
+    }
+
+    /**
+     * Set action text for the action button.
+     * @param actionText Text to be displayed.
+     */
+    void setActionText(String actionText) {
+        mActionButton.setText(actionText);
+    }
+
+    /**
+     * Set click listener for the action button.
+     * @param listener {@link android.view.View.OnClickListener} for the action button.
+     */
+    void setActionButtonOnClickListener(OnClickListener listener) {
+        mActionButton.setOnClickListener(listener);
+    }
+
+    /**
+     * Set content description for dismiss button.
+     * @param description The content description.
+     */
+    void setDismissButtonContentDescription(String description) {
+        mCloseButton.setContentDescription(description);
+    }
+
+    /**
+     * Set {@link android.view.View.OnClickListener} for dismiss button.
+     * @param listener {@link android.view.View.OnClickListener} to set.
+     */
+    void setDismissButtonOnClickListener(OnClickListener listener) {
+        mCloseButton.setOnClickListener(listener);
+    }
+
+    /**
+     * Set price strings for the price info box.
+     */
+    void setPriceInfoBoxStrings(ShoppingPersistedTabData.PriceDrop priceDrop) {
+        mPriceInfoBox.setPriceStrings(priceDrop.price, priceDrop.previousPrice);
+    }
+}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardViewBinder.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tasks.tab_management;
+
+import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.CARD_ALPHA;
+
+import android.view.ViewGroup;
+
+import org.chromium.chrome.browser.tab.state.ShoppingPersistedTabData;
+import org.chromium.ui.modelutil.PropertyKey;
+import org.chromium.ui.modelutil.PropertyModel;
+
+/**
+ * ViewBinder for PriceWelcomeMessageCardItem.
+ */
+class PriceWelcomeMessageCardViewBinder {
+    public static void bind(PropertyModel model, ViewGroup view, PropertyKey propertyKey) {
+        assert view instanceof PriceWelcomeMessageCardView;
+
+        PriceWelcomeMessageCardView itemView = (PriceWelcomeMessageCardView) view;
+        if (MessageCardViewProperties.ACTION_TEXT == propertyKey) {
+            itemView.setActionText(model.get(MessageCardViewProperties.ACTION_TEXT));
+            itemView.setActionButtonOnClickListener(v -> {
+                MessageCardView.ReviewActionProvider uiProvider =
+                        model.get(MessageCardViewProperties.UI_ACTION_PROVIDER);
+                if (uiProvider != null) uiProvider.review();
+
+                MessageCardView.ReviewActionProvider serviceProvider =
+                        model.get(MessageCardViewProperties.MESSAGE_SERVICE_ACTION_PROVIDER);
+                if (serviceProvider != null) serviceProvider.review();
+
+                MessageCardView.DismissActionProvider uiDismissProvider =
+                        model.get(MessageCardViewProperties.UI_DISMISS_ACTION_PROVIDER);
+                if (uiDismissProvider != null
+                        && !model.get(MessageCardViewProperties.SHOULD_KEEP_AFTER_REVIEW)) {
+                    uiDismissProvider.dismiss(model.get(MessageCardViewProperties.MESSAGE_TYPE));
+                }
+            });
+        } else if (MessageCardViewProperties.TITLE_TEXT == propertyKey) {
+            itemView.setTitleText(model.get(MessageCardViewProperties.TITLE_TEXT));
+        } else if (MessageCardViewProperties.DESCRIPTION_TEXT == propertyKey) {
+            itemView.setContentText(model.get(MessageCardViewProperties.DESCRIPTION_TEXT));
+        } else if (MessageCardViewProperties.DISMISS_BUTTON_CONTENT_DESCRIPTION == propertyKey) {
+            itemView.setDismissButtonContentDescription(
+                    model.get(MessageCardViewProperties.DISMISS_BUTTON_CONTENT_DESCRIPTION));
+            itemView.setDismissButtonOnClickListener(v -> {
+                int type = model.get(MessageCardViewProperties.MESSAGE_TYPE);
+                MessageCardView.DismissActionProvider uiProvider =
+                        model.get(MessageCardViewProperties.UI_DISMISS_ACTION_PROVIDER);
+                if (uiProvider != null) uiProvider.dismiss(type);
+
+                MessageCardView.DismissActionProvider serviceProvider = model.get(
+                        MessageCardViewProperties.MESSAGE_SERVICE_DISMISS_ACTION_PROVIDER);
+                if (serviceProvider != null) serviceProvider.dismiss(type);
+            });
+        } else if (MessageCardViewProperties.PRICE_DROP == propertyKey) {
+            ShoppingPersistedTabData.PriceDrop priceDrop =
+                    model.get(MessageCardViewProperties.PRICE_DROP);
+            if (priceDrop != null) itemView.setPriceInfoBoxStrings(priceDrop);
+        } else if (CARD_ALPHA == propertyKey) {
+            itemView.setAlpha(model.get(CARD_ALPHA));
+        }
+    }
+}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageCardViewModel.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tasks.tab_management;
+
+import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.CARD_ALPHA;
+import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.CARD_TYPE;
+import static org.chromium.chrome.browser.tasks.tab_management.TabListModel.CardProperties.ModelType.MESSAGE;
+
+import android.content.Context;
+
+import org.chromium.chrome.tab_ui.R;
+import org.chromium.ui.modelutil.PropertyModel;
+
+/**
+ * This is a util class for creating the property model of the {@link PriceWelcomeMessageCardView}.
+ */
+public class PriceWelcomeMessageCardViewModel {
+    /**
+     * Create a {@link PropertyModel} for {@link PriceWelcomeMessageCardView}.
+     * @param context The {@link Context} to use.
+     * @param uiDismissActionProvider The {@link MessageCardView.DismissActionProvider} to set.
+     * @param data The {@link PriceWelcomeMessageService.PriceWelcomeMessageData} to use.
+     * @return A {@link PropertyModel} for the given {@code data}.
+     */
+    public static PropertyModel create(Context context,
+            MessageCardView.DismissActionProvider uiDismissActionProvider,
+            PriceWelcomeMessageService.PriceWelcomeMessageData data) {
+        String titleText = context.getString(R.string.price_drop_spotted_title);
+        String contentText = context.getString(R.string.price_drop_spotted_content);
+        String actionText = context.getString(R.string.price_drop_spotted_show_me);
+        String dismissButtonContextDescription =
+                context.getString(R.string.accessibility_tab_suggestion_dismiss_button);
+
+        return new PropertyModel.Builder(MessageCardViewProperties.ALL_KEYS)
+                .with(MessageCardViewProperties.MESSAGE_TYPE,
+                        MessageService.MessageType.PRICE_WELCOME)
+                .with(MessageCardViewProperties.UI_DISMISS_ACTION_PROVIDER, uiDismissActionProvider)
+                .with(MessageCardViewProperties.MESSAGE_SERVICE_DISMISS_ACTION_PROVIDER,
+                        data.getDismissActionProvider())
+                .with(MessageCardViewProperties.MESSAGE_SERVICE_ACTION_PROVIDER,
+                        data.getReviewActionProvider())
+                .with(MessageCardViewProperties.DESCRIPTION_TEXT, contentText)
+                .with(MessageCardViewProperties.DESCRIPTION_TEXT_TEMPLATE, null)
+                .with(MessageCardViewProperties.ACTION_TEXT, actionText)
+                .with(MessageCardViewProperties.DISMISS_BUTTON_CONTENT_DESCRIPTION,
+                        dismissButtonContextDescription)
+                .with(MessageCardViewProperties.SHOULD_KEEP_AFTER_REVIEW, false)
+                .with(MessageCardViewProperties.IS_ICON_VISIBLE, false)
+                .with(MessageCardViewProperties.IS_INCOGNITO, false)
+                .with(MessageCardViewProperties.TITLE_TEXT, titleText)
+                .with(MessageCardViewProperties.PRICE_DROP, data.getPriceDrop())
+                .with(CARD_TYPE, MESSAGE)
+                .with(CARD_ALPHA, 1f)
+                .build();
+    }
+}
\ No newline at end of file

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/PriceWelcomeMessageService.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tasks.tab_management;
+
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.browser.tab.state.ShoppingPersistedTabData;
+
+/**
+ * One of the concrete {@link MessageService} that only serves {@link MessageType#PRICE_WELCOME}.
+ */
+public class PriceWelcomeMessageService extends MessageService {
+    /**
+     * Provides the binding tab ID and the price drop of the binding tab.
+     */
+    static class PriceTabData {
+        public final int bindingTabId;
+        public final ShoppingPersistedTabData.PriceDrop priceDrop;
+
+        PriceTabData(int bindingTabId, ShoppingPersistedTabData.PriceDrop priceDrop) {
+            this.bindingTabId = bindingTabId;
+            this.priceDrop = priceDrop;
+        }
+
+        @Override
+        public boolean equals(Object object) {
+            if (!(object instanceof PriceTabData)) return false;
+            PriceTabData priceTabData = (PriceTabData) object;
+            return this.bindingTabId == priceTabData.bindingTabId
+                    && this.priceDrop.equals(priceTabData.priceDrop);
+        }
+
+        @Override
+        public int hashCode() {
+            int result = 17;
+            result = 31 * result + bindingTabId;
+            result = 31 * result + (priceDrop == null ? 0 : priceDrop.hashCode());
+            return result;
+        }
+    }
+
+    /**
+     * An interface to help build the PriceWelcomeMessage.
+     */
+    public interface PriceWelcomeMessageProvider {
+        /**
+         * This method gets the information of the first tab showing price card.
+         *
+         * @return The PriceTabData including the tab ID and the price drop.
+         */
+        PriceTabData getFirstTabShowingPriceCard();
+
+        /**
+         * This method gets the tab index from tab ID.
+         *
+         * @param tabId The tab ID to search for.
+         * @return the index within the {@link TabListModel}.
+         */
+        int getTabIndexFromTabId(int tabId);
+    }
+
+    /**
+     * An interface to handle the review action of PriceWelcomeMessage.
+     */
+    public interface PriceWelcomeMessageReviewActionProvider {
+        /**
+         * This method scrolls to the binding tab of the PriceWelcomeMessage.
+         *
+         * @param tabIndex The index of the {@link Tab} that is binding to PriceWelcomeMessage.
+         */
+        void scrollToBindingTab(int tabIndex);
+    }
+
+    /**
+     * This is the data type that this MessageService is serving to its Observer.
+     */
+    class PriceWelcomeMessageData implements MessageData {
+        private final ShoppingPersistedTabData.PriceDrop mPriceDrop;
+        private final MessageCardView.ReviewActionProvider mReviewActionProvider;
+        private final MessageCardView.DismissActionProvider mDismissActionProvider;
+
+        PriceWelcomeMessageData(ShoppingPersistedTabData.PriceDrop priceDrop,
+                MessageCardView.ReviewActionProvider reviewActionProvider,
+                MessageCardView.DismissActionProvider dismissActionProvider) {
+            mPriceDrop = priceDrop;
+            mReviewActionProvider = reviewActionProvider;
+            mDismissActionProvider = dismissActionProvider;
+        }
+
+        /**
+         * @return The {@link MessageCardViewProperties#PRICE_DROP} for the associated
+         *         PRICE_WELCOME.
+         */
+        ShoppingPersistedTabData.PriceDrop getPriceDrop() {
+            return mPriceDrop;
+        }
+
+        /**
+         * @return The {@link MessageCardView.ReviewActionProvider} for the associated
+         *         PRICE_WELCOME.
+         */
+        MessageCardView.ReviewActionProvider getReviewActionProvider() {
+            return mReviewActionProvider;
+        }
+
+        /**
+         * @return The {@link MessageCardView.DismissActionProvider} for the associated
+         *         PRICE_WELCOME.
+         */
+        MessageCardView.DismissActionProvider getDismissActionProvider() {
+            return mDismissActionProvider;
+        }
+    }
+
+    private final PriceWelcomeMessageProvider mPriceWelcomeMessageProvider;
+    private final PriceWelcomeMessageReviewActionProvider mPriceWelcomeMessageReviewActionProvider;
+
+    private PriceTabData mPriceTabData;
+
+    PriceWelcomeMessageService(PriceWelcomeMessageProvider priceWelcomeMessageProvider,
+            PriceWelcomeMessageReviewActionProvider priceWelcomeMessageReviewActionProvider) {
+        super(MessageType.PRICE_WELCOME);
+        mPriceTabData = null;
+        mPriceWelcomeMessageProvider = priceWelcomeMessageProvider;
+        mPriceWelcomeMessageReviewActionProvider = priceWelcomeMessageReviewActionProvider;
+    }
+
+    void preparePriceMessage() {
+        if (PriceTrackingUtilities.isPriceWelcomeMessageCardDisabled()) return;
+        PriceTabData priceTabData = mPriceWelcomeMessageProvider.getFirstTabShowingPriceCard();
+        if (priceTabData == null) {
+            mPriceTabData = null;
+            sendInvalidNotification();
+        } else if (!priceTabData.equals(mPriceTabData)) {
+            mPriceTabData = priceTabData;
+            sendInvalidNotification();
+            sendAvailabilityNotification(new PriceWelcomeMessageData(
+                    mPriceTabData.priceDrop, this::review, (int messageType) -> dismiss()));
+        }
+    }
+
+    private void review() {
+        assert mPriceTabData != null;
+        mPriceWelcomeMessageReviewActionProvider.scrollToBindingTab(
+                mPriceWelcomeMessageProvider.getTabIndexFromTabId(mPriceTabData.bindingTabId));
+        PriceTrackingUtilities.disablePriceWelcomeMessageCard();
+    }
+
+    private void dismiss() {
+        PriceTrackingUtilities.disablePriceWelcomeMessageCard();
+    }
+}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabGridItemTouchHelperCallback.java

@@ -101,6 +101,7 @@ public class TabGridItemTouchHelperCallback extends ItemTouchHelper.SimpleCallba
     public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
         final int dragFlags = viewHolder.getItemViewType() == TabProperties.UiType.MESSAGE
                         || viewHolder.getItemViewType() == TabProperties.UiType.NEW_TAB_TILE
+                        || viewHolder.getItemViewType() == TabProperties.UiType.PRICE_WELCOME
                 ? 0
                 : mDragFlags;
         final int swipeFlags = viewHolder.getItemViewType() == TabProperties.UiType.NEW_TAB_TILE
@@ -114,7 +115,8 @@ public class TabGridItemTouchHelperCallback extends ItemTouchHelper.SimpleCallba
     public boolean canDropOver(@NonNull RecyclerView recyclerView,
             @NonNull RecyclerView.ViewHolder current, @NonNull RecyclerView.ViewHolder target) {
         if (target.getItemViewType() == TabProperties.UiType.MESSAGE
-                || target.getItemViewType() == TabProperties.UiType.NEW_TAB_TILE) {
+                || target.getItemViewType() == TabProperties.UiType.NEW_TAB_TILE
+                || target.getItemViewType() == TabProperties.UiType.PRICE_WELCOME) {
             return false;
         }
         return super.canDropOver(recyclerView, current, target);

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabGridViewBinder.java

@@ -225,15 +225,19 @@ class TabGridViewBinder {
                         .fetch((shoppingPersistedTabData) -> {
                             if (shoppingPersistedTabData.getPriceDrop() == null) {
                                 priceCardView.setVisibility(View.GONE);
+                                model.set(TabProperties.PRICE_DROP, null);
                             } else {
                                 priceCardView.setPriceStrings(
                                         shoppingPersistedTabData.getPriceDrop().price,
                                         shoppingPersistedTabData.getPriceDrop().previousPrice);
                                 priceCardView.setVisibility(View.VISIBLE);
+                                model.set(TabProperties.PRICE_DROP,
+                                        shoppingPersistedTabData.getPriceDrop());
                             }
                         });
             } else {
                 priceCardView.setVisibility(View.GONE);
+                model.set(TabProperties.PRICE_DROP, null);
             }
         } else if (TabProperties.PAGE_INFO_LISTENER == propertyKey) {
             TabListMediator.TabActionListener listener =

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListCoordinator.java

@@ -30,6 +30,7 @@ import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.chrome.browser.tasks.pseudotab.PseudoTab;
+import org.chromium.chrome.browser.tasks.tab_management.PriceWelcomeMessageService.PriceTabData;
 import org.chromium.chrome.browser.tasks.tab_management.TabProperties.UiType;
 import org.chromium.chrome.features.start_surface.StartSurfaceConfiguration;
 import org.chromium.chrome.tab_ui.R;
@@ -48,7 +49,8 @@ import java.util.List;
 /**
  * Coordinator for showing UI for a list of tabs. Can be used in GRID or STRIP modes.
  */
-public class TabListCoordinator implements Destroyable {
+public class TabListCoordinator
+        implements PriceWelcomeMessageService.PriceWelcomeMessageProvider, Destroyable {
     /**
      * Modes of showing the list of tabs.
      *
@@ -338,6 +340,13 @@ public class TabListCoordinator implements Destroyable {
         return tabListRect.top;
     }
 
+    /**
+     * @return The index of the model list where the PriceWelcomeMessage should be inserted.
+     */
+    int getPriceWelcomeMessageIndex() {
+        return mModel.size();
+    }
+
     /**
      * @return The container {@link androidx.recyclerview.widget.RecyclerView} that is showing the
      *         tab list UI.
@@ -444,4 +453,15 @@ public class TabListCoordinator implements Destroyable {
     void removeSpecialListItem(@UiType int uiType, int itemIdentifier) {
         mMediator.removeSpecialItemFromModel(uiType, itemIdentifier);
     }
+
+    // PriceWelcomeMessageService.PriceWelcomeMessageProvider implementation.
+    @Override
+    public PriceTabData getFirstTabShowingPriceCard() {
+        return mModel.getFirstTabShowingPriceCard();
+    }
+
+    @Override
+    public int getTabIndexFromTabId(int tabId) {
+        return mModel.indexFromId(tabId);
+    }
 }

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediator.java

@@ -1138,7 +1138,10 @@ class TabListMediator {
             public int getSpanSize(int position) {
                 int itemType = mModel.get(position).type;
 
-                if (itemType == TabProperties.UiType.MESSAGE) return manager.getSpanCount();
+                if (itemType == TabProperties.UiType.MESSAGE
+                        || itemType == TabProperties.UiType.PRICE_WELCOME) {
+                    return manager.getSpanCount();
+                }
                 return 1;
             }
         });
@@ -1286,6 +1289,7 @@ class TabListMediator {
                         .with(TabProperties.TABSTRIP_FAVICON_BACKGROUND_COLOR_ID,
                                 tabstripFaviconBackgroundDrawableId)
                         .with(TabProperties.ACCESSIBILITY_DELEGATE, mAccessibilityDelegate)
+                        .with(TabProperties.PRICE_DROP, null)
                         .with(CARD_TYPE, TAB)
                         .build();
 
@@ -1562,7 +1566,7 @@ class TabListMediator {
      */
     void removeSpecialItemFromModel(@UiType int uiType, int itemIdentifier) {
         int index = TabModel.INVALID_TAB_INDEX;
-        if (uiType == UiType.MESSAGE) {
+        if (uiType == UiType.MESSAGE || uiType == UiType.PRICE_WELCOME) {
             if (itemIdentifier == MessageService.MessageType.ALL) {
                 while (mModel.lastIndexForMessageItem() != TabModel.INVALID_TAB_INDEX) {
                     index = mModel.lastIndexForMessageItem();
@@ -1582,7 +1586,7 @@ class TabListMediator {
     }
 
     private boolean validateItemAt(int index, @UiType int uiType, int itemIdentifier) {
-        if (uiType == UiType.MESSAGE) {
+        if (uiType == UiType.MESSAGE || uiType == UiType.PRICE_WELCOME) {
             return mModel.get(index).type == uiType
                     && mModel.get(index).model.get(MESSAGE_TYPE) == itemIdentifier;
         } else if (uiType == UiType.NEW_TAB_TILE) {

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListModel.java

@@ -19,6 +19,7 @@ import androidx.annotation.IntDef;
 
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabModel;
+import org.chromium.chrome.browser.tasks.tab_management.PriceWelcomeMessageService.PriceTabData;
 import org.chromium.ui.modelutil.MVCListAdapter;
 import org.chromium.ui.modelutil.MVCListAdapter.ModelList;
 import org.chromium.ui.modelutil.PropertyListModel;
@@ -203,4 +204,18 @@ class TabListModel extends ModelList {
 
         get(index).model.set(TabProperties.CARD_ANIMATION_STATUS, status);
     }
+
+    /**
+     * Get the first tab showing price card.
+     */
+    public PriceTabData getFirstTabShowingPriceCard() {
+        for (int i = 0; i < size(); i++) {
+            PropertyModel model = get(i).model;
+            if ((model.get(CARD_TYPE) == TAB) && (model.get(TabProperties.PRICE_DROP) != null)) {
+                return new PriceTabData(
+                        model.get(TabProperties.TAB_ID), model.get(TabProperties.PRICE_DROP));
+            }
+        }
+        return null;
+    }
 }

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabProperties.java

@@ -13,6 +13,7 @@ import android.view.View.AccessibilityDelegate;
 
 import androidx.annotation.IntDef;
 
+import org.chromium.chrome.browser.tab.state.ShoppingPersistedTabData;
 import org.chromium.components.browser_ui.widget.selectable_list.SelectionDelegate;
 import org.chromium.ui.modelutil.PropertyKey;
 import org.chromium.ui.modelutil.PropertyModel;
@@ -28,7 +29,7 @@ import java.lang.annotation.RetentionPolicy;
 public class TabProperties {
     /** IDs for possible types of UI in the tab list. */
     @IntDef({UiType.SELECTABLE, UiType.CLOSABLE, UiType.STRIP, UiType.MESSAGE, UiType.DIVIDER,
-            UiType.NEW_TAB_TILE})
+            UiType.NEW_TAB_TILE, UiType.PRICE_WELCOME})
     @Retention(RetentionPolicy.SOURCE)
     public @interface UiType {
         int SELECTABLE = 0;
@@ -37,6 +38,7 @@ public class TabProperties {
         int MESSAGE = 3;
         int DIVIDER = 4;
         int NEW_TAB_TILE = 5;
+        int PRICE_WELCOME = 6;
     }
 
     public static final PropertyModel.WritableIntPropertyKey TAB_ID =
@@ -118,6 +120,9 @@ public class TabProperties {
     public static final WritableObjectPropertyKey<String> CLOSE_BUTTON_DESCRIPTION_STRING =
             new WritableObjectPropertyKey<>();
 
+    public static final WritableObjectPropertyKey<ShoppingPersistedTabData.PriceDrop> PRICE_DROP =
+            new WritableObjectPropertyKey<>();
+
     public static final PropertyKey[] ALL_KEYS_TAB_GRID = new PropertyKey[] {TAB_ID,
             TAB_SELECTED_LISTENER, TAB_CLOSED_LISTENER, FAVICON, THUMBNAIL_FETCHER, IPH_PROVIDER,
             TITLE, IS_SELECTED, CHECKED_DRAWABLE_STATE_LIST, CREATE_GROUP_LISTENER, CARD_ALPHA,
@@ -127,7 +132,7 @@ public class TabProperties {
             SELECTABLE_TAB_ACTION_BUTTON_SELECTED_BACKGROUND, URL_DOMAIN, ACCESSIBILITY_DELEGATE,
             SEARCH_QUERY, PAGE_INFO_LISTENER, PAGE_INFO_ICON_DRAWABLE_ID, CARD_TYPE,
             CONTENT_DESCRIPTION_STRING, CLOSE_BUTTON_DESCRIPTION_STRING,
-            SHOPPING_PERSISTED_TAB_DATA_FETCHER};
+            SHOPPING_PERSISTED_TAB_DATA_FETCHER, PRICE_DROP};
 
     public static final PropertyKey[] ALL_KEYS_TAB_STRIP =
             new PropertyKey[] {TAB_ID, TAB_SELECTED_LISTENER, TAB_CLOSED_LISTENER, FAVICON,

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabSwitcherCoordinator.java

@@ -109,6 +109,7 @@ public class TabSwitcherCoordinator
     private ViewGroup mContainer;
     private TabCreatorManager mTabCreatorManager;
     private boolean mIsInitialized;
+    private PriceWelcomeMessageService mPriceWelcomeMessageService;
     private final ViewGroup mRootView;
 
     private final MenuOrKeyboardActionController
@@ -211,9 +212,14 @@ public class TabSwitcherCoordinator
 
         mMessageCardProviderCoordinator = new MessageCardProviderCoordinator(
                 context, tabModelSelector::isIncognitoSelected, (identifier) -> {
-                    mTabListCoordinator.removeSpecialListItem(
-                            TabProperties.UiType.MESSAGE, identifier);
-                    appendNextMessage(identifier);
+                    if (identifier == MessageService.MessageType.PRICE_WELCOME) {
+                        mTabListCoordinator.removeSpecialListItem(
+                                TabProperties.UiType.PRICE_WELCOME, identifier);
+                    } else {
+                        mTabListCoordinator.removeSpecialListItem(
+                                TabProperties.UiType.MESSAGE, identifier);
+                        appendNextMessage(identifier);
+                    }
                 });
 
         if (TabUiFeatureUtilities.isTabGroupsAndroidEnabled()) {
@@ -238,6 +244,12 @@ public class TabSwitcherCoordinator
                         new LayoutViewBuilder(R.layout.new_tab_tile_card_item),
                         NewTabTileViewBinder::bind);
             }
+
+            if (TabUiFeatureUtilities.isPriceTrackingEnabled()) {
+                mTabListCoordinator.registerItemType(TabProperties.UiType.PRICE_WELCOME,
+                        new LayoutViewBuilder(R.layout.price_welcome_message_card_item),
+                        PriceWelcomeMessageCardViewBinder::bind);
+            }
         }
 
         if (CachedFeatureFlags.isEnabled(ChromeFeatureList.INSTANT_START)
@@ -308,6 +320,13 @@ public class TabSwitcherCoordinator
                         new IphMessageService(mTabGridIphDialogCoordinator);
                 mMessageCardProviderCoordinator.subscribeMessageService(iphMessageService);
             }
+
+            if (TabUiFeatureUtilities.isPriceTrackingEnabled()) {
+                mPriceWelcomeMessageService =
+                        new PriceWelcomeMessageService(mTabListCoordinator, mMediator);
+                mMessageCardProviderCoordinator.subscribeMessageService(
+                        mPriceWelcomeMessageService);
+            }
         }
         mIsInitialized = true;
     }
@@ -435,10 +454,12 @@ public class TabSwitcherCoordinator
     public boolean resetWithTabs(
             @Nullable List<PseudoTab> tabs, boolean quickMode, boolean mruMode) {
         mMediator.registerFirstMeaningfulPaintRecorder();
+        // Make sure that before resetWithListOfTabs, there are no messages in the middle of tabs in
+        // our TabListModel.
+        removeAllAppendedMessage();
         boolean showQuickly = mTabListCoordinator.resetWithListOfTabs(tabs, quickMode, mruMode);
         if (showQuickly) {
             mTabListCoordinator.removeSpecialListItem(TabProperties.UiType.NEW_TAB_TILE, 0);
-            removeAllAppendedMessage();
         }
 
         int cardsCount = tabs == null ? 0 : tabs.size();
@@ -447,7 +468,13 @@ public class TabSwitcherCoordinator
                     mNewTabTileCoordinator.getModel());
             cardsCount += 1;
         }
-        if (tabs != null && tabs.size() > 0) appendMessagesTo(cardsCount);
+
+        if (tabs != null && tabs.size() > 0) {
+            if (mPriceWelcomeMessageService != null) {
+                mPriceWelcomeMessageService.preparePriceMessage();
+            }
+            appendMessagesTo(cardsCount);
+        }
 
         return showQuickly;
     }
@@ -466,8 +493,14 @@ public class TabSwitcherCoordinator
         List<MessageCardProviderMediator.Message> messages =
                 mMessageCardProviderCoordinator.getMessageItems();
         for (int i = 0; i < messages.size(); i++) {
-            mTabListCoordinator.addSpecialListItemToEnd(
-                    TabProperties.UiType.MESSAGE, messages.get(i).model);
+            if (messages.get(i).type == MessageService.MessageType.PRICE_WELCOME) {
+                mTabListCoordinator.addSpecialListItem(
+                        mTabListCoordinator.getPriceWelcomeMessageIndex(),
+                        TabProperties.UiType.PRICE_WELCOME, messages.get(i).model);
+            } else {
+                mTabListCoordinator.addSpecialListItemToEnd(
+                        TabProperties.UiType.MESSAGE, messages.get(i).model);
+            }
         }
         sAppendedMessagesForTesting = messages.size() > 0;
     }
@@ -478,8 +511,14 @@ public class TabSwitcherCoordinator
         List<MessageCardProviderMediator.Message> messages =
                 mMessageCardProviderCoordinator.getMessageItems();
         for (int i = 0; i < messages.size(); i++) {
-            mTabListCoordinator.addSpecialListItem(
-                    index + i, TabProperties.UiType.MESSAGE, messages.get(i).model);
+            if (messages.get(i).type == MessageService.MessageType.PRICE_WELCOME) {
+                mTabListCoordinator.addSpecialListItem(
+                        mTabListCoordinator.getPriceWelcomeMessageIndex(),
+                        TabProperties.UiType.PRICE_WELCOME, messages.get(i).model);
+            } else {
+                mTabListCoordinator.addSpecialListItem(
+                        index + i, TabProperties.UiType.MESSAGE, messages.get(i).model);
+            }
         }
         if (messages.size() > 0) sAppendedMessagesForTesting = true;
     }

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabSwitcherMediator.java

@@ -65,8 +65,10 @@ import java.util.List;
  * The Mediator that is responsible for resetting the tab grid or carousel based on visibility and
  * model changes.
  */
-class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView.VisibilityListener,
-                                     TabListMediator.GridCardOnClickListenerProvider {
+class TabSwitcherMediator
+        implements TabSwitcher.Controller, TabListRecyclerView.VisibilityListener,
+                   TabListMediator.GridCardOnClickListenerProvider,
+                   PriceWelcomeMessageService.PriceWelcomeMessageReviewActionProvider {
     private static final String TAG = "TabSwitcherMediator";
 
     // This should be the same as TabListCoordinator.GRID_LAYOUT_SPAN_COUNT for the selected tab
@@ -778,6 +780,11 @@ class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView
         }
     }
 
+    @Override
+    public void scrollToBindingTab(int tabIndex) {
+        mContainerViewModel.set(TabListContainerProperties.INITIAL_SCROLL_INDEX, tabIndex);
+    }
+
     private boolean ableToOpenDialog(Tab tab) {
         return TabUiFeatureUtilities.isTabGroupsAndroidEnabled()
                 && mTabModelSelector.isIncognitoSelected() == tab.isIncognito()

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeys.java

@@ -531,6 +531,11 @@ public final class ChromePreferenceKeys {
     public static final String PREFETCH_NOTIFICATION_TIME = "prefetch_notification_shown_time";
     public static final String PREFETCH_OFFLINE_COUNTER = "prefetch_notification_offline_counter";
 
+    /**
+     * Whether users disable the PriceWelcomeMessageCard.
+     */
+    public static final String PRICE_TRACKING_PRICE_WELCOME_MESSAGE_CARD =
+            "Chrome.PriceTracking.PriceWelcome";
     /**
      * Whether users turn on the feature track prices on tabs.
      */
@@ -837,6 +842,7 @@ public final class ChromePreferenceKeys {
                 IMAGE_DESCRIPTIONS_JUST_ONCE_COUNT,
                 IMAGE_DESCRIPTIONS_DONT_ASK_AGAIN,
                 PERSISTENT_OFFLINE_CONTENT_AVAILABILITY_STATUS,
+                PRICE_TRACKING_PRICE_WELCOME_MESSAGE_CARD,
                 PRICE_TRACKING_TRACK_PRICES_ON_TABS,
                 PROMO_IS_DISMISSED.pattern(),
                 PROMO_TIMES_SEEN.pattern(),

chrome/browser/tab/java/src/org/chromium/chrome/browser/tab/state/ShoppingPersistedTabData.java

@@ -90,6 +90,22 @@ public class ShoppingPersistedTabData extends PersistedTabData {
             this.price = price;
             this.previousPrice = previousPrice;
         }
+
+        @Override
+        public boolean equals(Object object) {
+            if (!(object instanceof PriceDrop)) return false;
+            PriceDrop priceDrop = (PriceDrop) object;
+            return this.price.equals(priceDrop.price)
+                    && this.previousPrice.equals(priceDrop.previousPrice);
+        }
+
+        @Override
+        public int hashCode() {
+            int result = 17;
+            result = 31 * result + (price == null ? 0 : price.hashCode());
+            result = 31 * result + (previousPrice == null ? 0 : previousPrice.hashCode());
+            return result;
+        }
     }
 
     @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)