[EoC] Add alpha animation to menu button

Bug: 831782
Change-Id: I7558d68a41f30120b6c573b9752612215e35b115
Reviewed-on: https://chromium-review.googlesource.com/1031293Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554437}

chrome/android/java/src/org/chromium/chrome/browser/contextual_suggestions/ContextualSuggestionsMediator.java

@@ -239,6 +239,7 @@ class ContextualSuggestionsMediator
         mModel.setClusterList(new ClusterList(Collections.emptyList()));
         mModel.setCloseButtonOnClickListener(null);
         mModel.setMenuButtonVisibility(false);
+        mModel.setMenuButtonAlpha(0f);
         mModel.setMenuButtonDelegate(null);
         mModel.setDefaultToolbarClickListener(null);
         mModel.setTitle(null);
@@ -266,6 +267,7 @@ class ContextualSuggestionsMediator
             clearSuggestions();
         });
         mModel.setMenuButtonVisibility(false);
+        mModel.setMenuButtonAlpha(0f);
         mModel.setMenuButtonDelegate(this);
         mModel.setDefaultToolbarClickListener(view -> mCoordinator.expandBottomSheet());
         mModel.setTitle(title);
@@ -310,6 +312,11 @@ class ContextualSuggestionsMediator
             public void onSheetClosed(int reason) {
                 mModel.setMenuButtonVisibility(false);
             }
+
+            @Override
+            public void onTransitionPeekToHalf(float transitionFraction) {
+                mModel.setMenuButtonAlpha(transitionFraction);
+            }
         };
 
         mCoordinator.addBottomSheetObserver(mSheetObserver);

chrome/android/java/src/org/chromium/chrome/browser/contextual_suggestions/ContextualSuggestionsModel.java

@@ -23,6 +23,7 @@ class ContextualSuggestionsModel
     static class PropertyKey {
         static final PropertyKey CLOSE_BUTTON_ON_CLICK_LISTENER = new PropertyKey();
         static final PropertyKey MENU_BUTTON_VISIBILITY = new PropertyKey();
+        static final PropertyKey MENU_BUTTON_ALPHA = new PropertyKey();
         static final PropertyKey MENU_BUTTON_DELEGATE = new PropertyKey();
         static final PropertyKey TITLE = new PropertyKey();
         static final PropertyKey TOOLBAR_SHADOW_VISIBILITY = new PropertyKey();
@@ -81,6 +82,7 @@ class ContextualSuggestionsModel
     ClusterListObservable mClusterListObservable = new ClusterListObservable();
     private OnClickListener mCloseButtonOnClickListener;
     private boolean mMenuButtonVisibility;
+    private float mMenuButtonAlpha;
     private ListMenuButton.Delegate mMenuButtonDelegate;
     private OnClickListener mDefaultToolbarOnClickListener;
     private String mTitle;
@@ -118,6 +120,17 @@ class ContextualSuggestionsModel
         return mMenuButtonVisibility;
     }
 
+    /** @param alpha The opacity of the menu button. */
+    void setMenuButtonAlpha(float alpha) {
+        mMenuButtonAlpha = alpha;
+        notifyPropertyChanged(PropertyKey.MENU_BUTTON_ALPHA);
+    }
+
+    /** @return The opacity of the menu button. */
+    float getMenuButtonAlpha() {
+        return mMenuButtonAlpha;
+    }
+
     /** @param delegate The delegate for handles actions for the menu. */
     void setMenuButtonDelegate(ListMenuButton.Delegate delegate) {
         mMenuButtonDelegate = delegate;

chrome/android/java/src/org/chromium/chrome/browser/contextual_suggestions/ToolbarView.java

@@ -46,6 +46,10 @@ public class ToolbarView extends LinearLayout {
         mMenuButton.setVisibility(visible ? View.VISIBLE : View.GONE);
     }
 
+    void setMenuButtonAlpha(float alpha) {
+        mMenuButton.setAlpha(alpha);
+    }
+
     void setTitle(String title) {
         mTitle.setText(title);
     }

chrome/android/java/src/org/chromium/chrome/browser/contextual_suggestions/ToolbarViewBinder.java

@@ -19,6 +19,8 @@ class ToolbarViewBinder
             view.setCloseButtonOnClickListener(model.getCloseButtonOnClickListener());
         } else if (propertyKey == PropertyKey.MENU_BUTTON_VISIBILITY) {
             view.setMenuButtonVisibility(model.getMenuButtonVisibility());
+        } else if (propertyKey == PropertyKey.MENU_BUTTON_ALPHA) {
+            view.setMenuButtonAlpha(model.getMenuButtonAlpha());
         } else if (propertyKey == PropertyKey.MENU_BUTTON_DELEGATE) {
             view.setMenuButtonDelegate(model.getMenuButtonDelegate());
         } else if (propertyKey == PropertyKey.TITLE) {