AW: switch Dev UI to Fragments

This switches Dev UI from Activities to Fragments. The immediate user
benefit is smoother transitions when switching between tools, but this
opens up for opportunities for other navigation methods (ex. bottom nav
bar or nav drawer).

Bug: 1017532
Test: Tested system_webview_apk on L+, monochrome on N+, Trichrome on Q
Test: Click flag UI notification, verify it opens the flags UI fragment
Change-Id: I32eb7a9b2ada6395bad21488e6bd15c802131b7e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108919
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Hazem Ashmawy <hazems@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753124}

android_webview/nonembedded/BUILD.gn

@@ -34,8 +34,9 @@ android_library("nonembedded_java") {
 
 android_library("devui_java") {
   sources = [
-    "java/src/org/chromium/android_webview/devui/CrashesListActivity.java",
-    "java/src/org/chromium/android_webview/devui/FlagsActivity.java",
+    "java/src/org/chromium/android_webview/devui/CrashesListFragment.java",
+    "java/src/org/chromium/android_webview/devui/FlagsFragment.java",
+    "java/src/org/chromium/android_webview/devui/HomeFragment.java",
     "java/src/org/chromium/android_webview/devui/MainActivity.java",
     "java/src/org/chromium/android_webview/devui/PersistentErrorView.java",
     "java/src/org/chromium/android_webview/devui/WebViewPackageError.java",
@@ -57,6 +58,7 @@ android_library("devui_java") {
     "//base:base_java",
     "//components/minidump_uploader:minidump_uploader_java",
     "//third_party/android_deps:androidx_annotation_annotation_java",
+    "//third_party/android_deps:com_android_support_support_fragment_java",
     "//ui/android:ui_java",
   ]
   android_manifest_for_lint = system_webview_android_manifest
@@ -117,12 +119,13 @@ android_resources("icon_resources") {
 android_resources("devui_resources") {
   sources = [
     "java/res_devui/drawable/blue_circle.xml",
-    "java/res_devui/layout/activity_crashes_list.xml",
-    "java/res_devui/layout/activity_flags.xml",
     "java/res_devui/layout/activity_main.xml",
     "java/res_devui/layout/crashes_list_item_body.xml",
     "java/res_devui/layout/crashes_list_item_header.xml",
     "java/res_devui/layout/flag_states.xml",
+    "java/res_devui/layout/fragment_crashes_list.xml",
+    "java/res_devui/layout/fragment_flags.xml",
+    "java/res_devui/layout/fragment_home.xml",
     "java/res_devui/layout/persistent_error_message.xml",
     "java/res_devui/layout/toggleable_flag.xml",
     "java/res_devui/layout/two_line_list_item.xml",

android_webview/nonembedded/java/AndroidManifest.xml

@@ -51,20 +51,6 @@
                       android:targetActivity="org.chromium.android_webview.devui.MainActivity"
                       android:enabled="false"
                       android:process=":webview_apk" />  {# Explicit process required for monochrome compatibility. #}
-            <activity android:name="org.chromium.android_webview.devui.CrashesListActivity"
-                      android:label="WebView Crashes"
-                      android:theme="@style/Theme.DevUi.DayNight"
-                      android:launchMode="singleTop"
-                      android:taskAffinity="{{ manifest_package }}.org.chromium.android_webview.devui" {# Explicit taskAffinity to distinguish from monochrome browser task. #}
-                      android:process=":webview_apk">  {# Explicit process required for monochrome compatibility. #}
-            </activity>
-            <activity android:name="org.chromium.android_webview.devui.FlagsActivity"
-                      android:label="WebView Flags"
-                      android:theme="@style/Theme.DevUi.DayNight"
-                      android:launchMode="singleTop"
-                      android:taskAffinity="{{ manifest_package }}.org.chromium.android_webview.devui" {# Explicit taskAffinity to distinguish from monochrome browser task. #}
-                      android:process=":webview_apk">  {# Explicit process required for monochrome compatibility. #}
-            </activity>
             <!-- End of WebView Developer UI Activities -->
 
             <activity android:name="org.chromium.android_webview.nonembedded.LicenseActivity"

android_webview/nonembedded/java/res_devui/layout/activity_main.xml

@@ -15,8 +15,12 @@
         layout="@layout/persistent_error_message"
         android:id="@+id/webview_package_error"/>
 
-    <ListView
-        android:id="@+id/main_info_list"
+    <include
+        layout="@layout/persistent_error_message"
+        android:id="@+id/crash_consent_error"/>
+
+    <FrameLayout
+        android:id="@+id/content_fragment"
         android:layout_width="match_parent"
         android:layout_height="match_parent"/>
 

android_webview/nonembedded/java/res_devui/layout/activity_crashes_list.xml → android_webview/nonembedded/java/res_devui/layout/fragment_crashes_list.xml

@@ -11,14 +11,6 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-    <include
-        layout="@layout/persistent_error_message"
-        android:id="@+id/webview_package_error"/>
-
-    <include
-        layout="@layout/persistent_error_message"
-        android:id="@+id/crash_consent_error"/>
-
     <TextView
         android:id="@+id/crashes_summary_textview"
         android:layout_width="match_parent"

android_webview/nonembedded/java/res_devui/layout/activity_flags.xml → android_webview/nonembedded/java/res_devui/layout/fragment_flags.xml

@@ -12,10 +12,6 @@
     android:layout_height="match_parent"
     android:padding="10dp">
 
-    <include
-        layout="@layout/persistent_error_message"
-        android:id="@+id/webview_package_error"/>
-
     <!--suppress HardcodedText -->
     <TextView
         android:id="@+id/flags_warning"

android_webview/nonembedded/java/res_devui/layout/fragment_home.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright 2019 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.
+-->
+
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/fragment_home"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+  <ListView
+      android:id="@+id/main_info_list"
+      android:layout_width="match_parent"
+      android:layout_height="match_parent"/>
+
+</LinearLayout>

android_webview/nonembedded/java/res_devui/layout/persistent_error_message.xml

@@ -7,6 +7,7 @@
 
 <TextView
     xmlns:android="http://schemas.android.com/apk/res/android"
+    android:visibility="gone"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:textAppearance="?android:attr/textAppearanceMedium"

android_webview/nonembedded/java/src/org/chromium/android_webview/devui/FlagsActivity.java → android_webview/nonembedded/java/src/org/chromium/android_webview/devui/FlagsFragment.java

@@ -13,8 +13,7 @@ import android.content.ServiceConnection;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.os.RemoteException;
-import android.view.Menu;
-import android.view.MenuItem;
+import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewParent;
@@ -25,22 +24,23 @@ import android.widget.ListView;
 import android.widget.Spinner;
 import android.widget.TextView;
 
+import androidx.fragment.app.Fragment;
+
 import org.chromium.android_webview.common.DeveloperModeUtils;
 import org.chromium.android_webview.common.Flag;
 import org.chromium.android_webview.common.ProductionSupportedFlagList;
 import org.chromium.android_webview.common.services.IDeveloperUiService;
 import org.chromium.android_webview.common.services.ServiceNames;
-import org.chromium.android_webview.devui.util.NavigationMenuHelper;
 import org.chromium.base.Log;
 
 import java.util.HashMap;
 import java.util.Map;
 
 /**
- * An activity to toggle experimental WebView flags/features.
+ * A fragment to toggle experimental WebView flags/features.
  */
 @SuppressLint("SetTextI18n")
-public class FlagsActivity extends Activity {
+public class FlagsFragment extends Fragment {
     private static final String TAG = "WebViewDevTools";
 
     private static final String STATE_DEFAULT = "Default";
@@ -52,46 +52,45 @@ public class FlagsActivity extends Activity {
             STATE_DISABLED,
     };
 
-    private WebViewPackageError mDifferentPackageError;
     private Map<String, Boolean> mOverriddenFlags = new HashMap<>();
     private FlagsListAdapter mListAdapter;
 
+    private Context mContext;
+
     @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
+    public void onAttach(Context context) {
+        super.onAttach(context);
+        mContext = context;
+    }
 
-        setContentView(R.layout.activity_flags);
+    @Override
+    public View onCreateView(
+            LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        return inflater.inflate(R.layout.fragment_flags, null);
+    }
 
-        ListView flagsListView = findViewById(R.id.flags_list);
-        TextView flagsDescriptionView = findViewById(R.id.flags_description);
+    @Override
+    public void onViewCreated(View view, Bundle savedInstanceState) {
+        Activity activity = (Activity) mContext;
+        activity.setTitle("WebView Flags");
+
+        ListView flagsListView = view.findViewById(R.id.flags_list);
+        TextView flagsDescriptionView = view.findViewById(R.id.flags_description);
         flagsDescriptionView.setText("By enabling these features, you could "
                 + "lose app data or compromise your security or privacy. Enabled features apply to "
                 + "WebViews across all apps on the device.");
 
         // Restore flag overrides from the service process to repopulate the UI, if developer mode
         // is enabled.
-        if (DeveloperModeUtils.isDeveloperModeEnabled(getPackageName())) {
-            mOverriddenFlags = DeveloperModeUtils.getFlagOverrides(getPackageName());
+        if (DeveloperModeUtils.isDeveloperModeEnabled(mContext.getPackageName())) {
+            mOverriddenFlags = DeveloperModeUtils.getFlagOverrides(mContext.getPackageName());
         }
 
         mListAdapter = new FlagsListAdapter();
         flagsListView.setAdapter(mListAdapter);
 
-        Button resetFlagsButton = findViewById(R.id.reset_flags_button);
-        resetFlagsButton.setOnClickListener((View view) -> { resetAllFlags(); });
-
-        mDifferentPackageError = new WebViewPackageError(this);
-        // show the dialog once when the activity is created.
-        mDifferentPackageError.showDialogIfDifferent();
-    }
-
-    @Override
-    protected void onResume() {
-        super.onResume();
-        // Check package status in onResume() to hide/show the error message if the user
-        // changes WebView implementation from system settings and then returns back to the
-        // activity.
-        mDifferentPackageError.showMessageIfDifferent();
+        Button resetFlagsButton = view.findViewById(R.id.reset_flags_button);
+        resetFlagsButton.setOnClickListener((View flagButton) -> { resetAllFlags(); });
     }
 
     private static int booleanToState(Boolean b) {
@@ -150,8 +149,7 @@ public class FlagsActivity extends Activity {
      */
     private class FlagsListAdapter extends ArrayAdapter<Flag> {
         public FlagsListAdapter() {
-            super(FlagsActivity.this, R.layout.toggleable_flag,
-                    ProductionSupportedFlagList.sFlagList);
+            super(mContext, R.layout.toggleable_flag, ProductionSupportedFlagList.sFlagList);
         }
 
         @Override
@@ -174,7 +172,7 @@ public class FlagsActivity extends Activity {
             flagName.setText(label);
             flagDescription.setText(flag.getDescription());
             ArrayAdapter<String> adapter =
-                    new ArrayAdapter<>(FlagsActivity.this, R.layout.flag_states, sFlagStates);
+                    new ArrayAdapter<>(mContext, R.layout.flag_states, sFlagStates);
             adapter.setDropDownViewResource(android.R.layout.select_dialog_singlechoice);
             flagToggle.setAdapter(adapter);
 
@@ -207,26 +205,11 @@ public class FlagsActivity extends Activity {
         }
     }
 
-    @Override
-    public boolean onCreateOptionsMenu(Menu menu) {
-        NavigationMenuHelper.inflate(this, menu);
-        return true;
-    }
-
-    @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
-        if (NavigationMenuHelper.onOptionsItemSelected(this, item)) {
-            return true;
-        }
-        return super.onOptionsItemSelected(item);
-    }
-
     private class FlagsServiceConnection implements ServiceConnection {
         public void start() {
             Intent intent = new Intent();
-            intent.setClassName(
-                    FlagsActivity.this.getPackageName(), ServiceNames.DEVELOPER_UI_SERVICE);
-            if (!FlagsActivity.this.bindService(intent, this, Context.BIND_AUTO_CREATE)) {
+            intent.setClassName(mContext.getPackageName(), ServiceNames.DEVELOPER_UI_SERVICE);
+            if (!mContext.bindService(intent, this, Context.BIND_AUTO_CREATE)) {
                 Log.e(TAG, "Failed to bind to Developer UI service");
             }
         }
@@ -234,8 +217,7 @@ public class FlagsActivity extends Activity {
         @Override
         public void onServiceConnected(ComponentName name, IBinder service) {
             Intent intent = new Intent();
-            intent.setClassName(
-                    FlagsActivity.this.getPackageName(), ServiceNames.DEVELOPER_UI_SERVICE);
+            intent.setClassName(mContext.getPackageName(), ServiceNames.DEVELOPER_UI_SERVICE);
             try {
                 IDeveloperUiService.Stub.asInterface(service).setFlagOverrides(mOverriddenFlags);
             } catch (RemoteException e) {
@@ -243,7 +225,7 @@ public class FlagsActivity extends Activity {
             } finally {
                 // Unbind when we've sent the flags overrides, since we can always rebind later. The
                 // service will manage its own lifetime.
-                FlagsActivity.this.unbindService(this);
+                mContext.unbindService(this);
             }
         }
 

android_webview/nonembedded/java/src/org/chromium/android_webview/devui/HomeFragment.java

+// Copyright 2019 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.android_webview.devui;
+
+import android.app.Activity;
+import android.content.ClipData;
+import android.content.ClipboardManager;
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.os.Build;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.ListView;
+import android.widget.TextView;
+
+import androidx.fragment.app.Fragment;
+
+import org.chromium.android_webview.devui.util.WebViewPackageHelper;
+import org.chromium.ui.widget.Toast;
+
+import java.util.Locale;
+
+/**
+ * Dev UI main fragment.
+ * It shows a summary about WebView package and the device.
+ */
+public class HomeFragment extends Fragment {
+    private Context mContext;
+
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+        mContext = context;
+    }
+
+    @Override
+    public View onCreateView(
+            LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        return inflater.inflate(R.layout.fragment_home, null);
+    }
+
+    @Override
+    public void onViewCreated(View view, Bundle savedInstanceState) {
+        Activity activity = (Activity) mContext;
+        activity.setTitle("WebView DevTools");
+
+        PackageInfo webViewPackage = WebViewPackageHelper.getContextPackageInfo(mContext);
+        InfoItem[] infoItems = new InfoItem[] {
+                new InfoItem("WebView package", webViewPackage.packageName),
+                new InfoItem("WebView version",
+                        String.format(Locale.US, "%s (%s)", webViewPackage.versionName,
+                                webViewPackage.versionCode)),
+                new InfoItem("Device info",
+                        String.format(Locale.US, "%s - %s", Build.MODEL, Build.FINGERPRINT)),
+        };
+
+        ListView infoListView = view.findViewById(R.id.main_info_list);
+        ArrayAdapter<InfoItem> itemsArrayAdapter = new InfoListAdapter(infoItems);
+        infoListView.setAdapter(itemsArrayAdapter);
+
+        // Copy item's text to clipboard on long tapping a list item.
+        infoListView.setOnItemLongClickListener((parent, clickedView, pos, id) -> {
+            InfoItem item = (InfoItem) parent.getItemAtPosition(pos);
+            ClipboardManager clipboard =
+                    (ClipboardManager) mContext.getSystemService(Context.CLIPBOARD_SERVICE);
+            ClipData clip = ClipData.newPlainText(item.title, item.subtitle);
+            clipboard.setPrimaryClip(clip);
+            // Show a toast that the text has been copied.
+            Toast.makeText(mContext, "Copied " + item.title, Toast.LENGTH_SHORT).show();
+
+            return true;
+        });
+    }
+
+    /**
+     * A model class for a key-value piece of information to be displayed as a title (key) and
+     * subtitle (value).
+     */
+    private static class InfoItem {
+        public static final String UNKNOWN = "Unknown";
+        public final String title;
+        public final String subtitle;
+
+        public InfoItem(String title, String subtitle) {
+            this.title = title;
+            this.subtitle = subtitle == null ? UNKNOWN : subtitle;
+        }
+    }
+
+    /**
+     * An ArrayAdapter to show a list of {@code InfoItem} objects.
+     *
+     * It uses android stock {@code android.R.layout.simple_list_item_2} which has two {@code
+     * TextView}; {@code text1} acts as the item title and {@code text2} as the item subtitle.
+     */
+    private class InfoListAdapter extends ArrayAdapter<InfoItem> {
+        private final InfoItem[] mItems;
+
+        public InfoListAdapter(InfoItem[] items) {
+            super(mContext, R.layout.two_line_list_item, items);
+            mItems = items;
+        }
+
+        @Override
+        public View getView(int position, View view, ViewGroup parent) {
+            // If the the old view is already created then reuse it, else create a new one by layout
+            // inflation.
+            if (view == null) {
+                view = getLayoutInflater().inflate(R.layout.two_line_list_item, null, true);
+            }
+
+            InfoItem item = mItems[position];
+            TextView title = view.findViewById(android.R.id.text1);
+            TextView subtitle = view.findViewById(android.R.id.text2);
+
+            title.setText(item.title);
+            subtitle.setText(item.subtitle);
+
+            return view;
+        }
+    }
+}

android_webview/nonembedded/java/src/org/chromium/android_webview/devui/MainActivity.java

@@ -3,34 +3,31 @@
 // found in the LICENSE file.
 package org.chromium.android_webview.devui;
 
-import android.app.Activity;
-import android.content.ClipData;
-import android.content.ClipboardManager;
-import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.os.Build;
+import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.ArrayAdapter;
-import android.widget.ListView;
-import android.widget.TextView;
 
-import org.chromium.android_webview.devui.util.NavigationMenuHelper;
-import org.chromium.android_webview.devui.util.WebViewPackageHelper;
-import org.chromium.ui.widget.Toast;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
 
-import java.util.Locale;
+import org.chromium.android_webview.devui.util.NavigationMenuHelper;
 
 /**
  * Dev UI main activity.
- * It shows a summary about WebView package and the device.
- * It helps to navigate to other WebView developer tools.
+ * It shows persistent errors and helps to navigate to WebView developer tools.
  */
-public class MainActivity extends Activity {
+public class MainActivity extends FragmentActivity {
     private WebViewPackageError mDifferentPackageError;
+    private boolean mSwitchFragmentOnResume;
+
+    // Keep in sync with DeveloperUiService.java
+    private static final String FRAGMENT_ID_INTENT_EXTRA = "fragment-id";
+    private static final int FRAGMENT_ID_HOME = 0;
+    private static final int FRAGMENT_ID_CRASHES = 1;
+    private static final int FRAGMENT_ID_FLAGS = 2;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -38,38 +35,22 @@ public class MainActivity extends Activity {
 
         setContentView(R.layout.activity_main);
 
-        PackageInfo webViewPackage = WebViewPackageHelper.getContextPackageInfo(this);
-        InfoItem[] infoItems = new InfoItem[] {
-                new InfoItem("WebView package", webViewPackage.packageName),
-                new InfoItem("WebView version",
-                        String.format(Locale.US, "%s (%s)", webViewPackage.versionName,
-                                webViewPackage.versionCode)),
-                new InfoItem("Device info",
-                        String.format(Locale.US, "%s - %s", Build.MODEL, Build.FINGERPRINT)),
-        };
-
-        ListView infoListView = findViewById(R.id.main_info_list);
-        ArrayAdapter<InfoItem> itemsArrayAdapter = new InfoListAdapter(infoItems);
-        infoListView.setAdapter(itemsArrayAdapter);
-
-        // Copy item's text to clipboard on long tapping a list item.
-        infoListView.setOnItemLongClickListener((parent, view, pos, id) -> {
-            InfoItem item = (InfoItem) parent.getItemAtPosition(pos);
-            ClipboardManager clipboard =
-                    (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
-            ClipData clip = ClipData.newPlainText(item.title, item.subtitle);
-            clipboard.setPrimaryClip(clip);
-            // Show a toast that the text has been copied.
-            Toast.makeText(MainActivity.this, "Copied " + item.title, Toast.LENGTH_SHORT).show();
-
-            return true;
-        });
+        // Let onResume handle showing the initial Fragment.
+        mSwitchFragmentOnResume = true;
 
         mDifferentPackageError = new WebViewPackageError(this);
         // show the dialog once when the activity is created.
         mDifferentPackageError.showDialogIfDifferent();
     }
 
+    @Override
+    protected void onNewIntent(Intent intent) {
+        // Store the Intent so we can switch Fragments in onResume (which is called next). Only need
+        // to switch Fragment if the Intent specifies to do so.
+        setIntent(intent);
+        mSwitchFragmentOnResume = intent.hasExtra(FRAGMENT_ID_INTENT_EXTRA);
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
@@ -77,54 +58,44 @@ public class MainActivity extends Activity {
         // changes WebView implementation from system settings and then returns back to the
         // activity.
         mDifferentPackageError.showMessageIfDifferent();
-    }
 
-    /**
-     * A model class for a key-value piece of information to be displayed as a title (key) and
-     * subtitle (value).
-     */
-    private static class InfoItem {
-        public static final String UNKNOWN = "Unknown";
-        public final String title;
-        public final String subtitle;
-
-        public InfoItem(String title, String subtitle) {
-            this.title = title;
-            this.subtitle = subtitle == null ? UNKNOWN : subtitle;
+        // Don't change Fragment unless we have a new Intent, since the user might just be coming
+        // back to this through the task switcher.
+        if (!mSwitchFragmentOnResume) return;
+
+        // Ensure we only switch the first time we see a new Intent.
+        mSwitchFragmentOnResume = false;
+
+        // Default to HomeFragment if not specified.
+        int fragmentId = FRAGMENT_ID_HOME;
+        // FRAGMENT_ID_INTENT_EXTRA is an optional extra to specify which fragment to open. At the
+        // moment, it's specified only by DeveloperUiService (so make sure these constants stay in
+        // sync).
+        Bundle extras = getIntent().getExtras();
+        if (extras != null) {
+            fragmentId = extras.getInt(FRAGMENT_ID_INTENT_EXTRA, fragmentId);
         }
-    }
 
-    /**
-     * An ArrayAdapter to show a list of {@code InfoItem} objects.
-     *
-     * It uses android stock {@code android.R.layout.simple_list_item_2} which has two {@code
-     * TextView}; {@code text1} acts as the item title and {@code text2} as the item subtitle.
-     */
-    private class InfoListAdapter extends ArrayAdapter<InfoItem> {
-        private final InfoItem[] mItems;
-
-        public InfoListAdapter(InfoItem[] items) {
-            super(MainActivity.this, R.layout.two_line_list_item, items);
-            mItems = items;
+        Fragment fragment = null;
+        switch (fragmentId) {
+            default:
+                // Fall through.
+            case FRAGMENT_ID_HOME:
+                fragment = new HomeFragment();
+                break;
+            case FRAGMENT_ID_CRASHES:
+                fragment = new CrashesListFragment();
+                break;
+            case FRAGMENT_ID_FLAGS:
+                fragment = new FlagsFragment();
+                break;
         }
+        assert fragment != null;
 
-        @Override
-        public View getView(int position, View view, ViewGroup parent) {
-            // If the the old view is already created then reuse it, else create a new one by layout
-            // inflation.
-            if (view == null) {
-                view = getLayoutInflater().inflate(R.layout.two_line_list_item, null, true);
-            }
-
-            InfoItem item = mItems[position];
-            TextView title = view.findViewById(android.R.id.text1);
-            TextView subtitle = view.findViewById(android.R.id.text2);
-
-            title.setText(item.title);
-            subtitle.setText(item.subtitle);
-
-            return view;
-        }
+        FragmentManager fm = getSupportFragmentManager();
+        FragmentTransaction transaction = fm.beginTransaction();
+        transaction.replace(R.id.content_fragment, fragment);
+        transaction.commit();
     }
 
     @Override

android_webview/nonembedded/java/src/org/chromium/android_webview/devui/util/NavigationMenuHelper.java

@@ -3,16 +3,20 @@
 // found in the LICENSE file.
 package org.chromium.android_webview.devui.util;
 
-import android.app.Activity;
 import android.content.Intent;
 import android.os.Build;
 import android.provider.Settings;
 import android.view.Menu;
 import android.view.MenuItem;
 
-import org.chromium.android_webview.devui.CrashesListActivity;
-import org.chromium.android_webview.devui.FlagsActivity;
-import org.chromium.android_webview.devui.MainActivity;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
+
+import org.chromium.android_webview.devui.CrashesListFragment;
+import org.chromium.android_webview.devui.FlagsFragment;
+import org.chromium.android_webview.devui.HomeFragment;
 import org.chromium.android_webview.devui.R;
 
 /**
@@ -24,9 +28,10 @@ public final class NavigationMenuHelper {
     /**
      * Inflate the navigation menu in the given {@code activity} options menu.
      *
-     * This should be called inside {@code Activity#onCreateOptionsMenu} method.
+     * This should be called inside {@link android.app.Activity#onCreateOptionsMenu} or
+     * {@link Fragment#onCreateOptionsMenu}.
      */
-    public static void inflate(Activity activity, Menu menu) {
+    public static void inflate(FragmentActivity activity, Menu menu) {
         activity.getMenuInflater().inflate(R.menu.navigation_menu, menu);
 
         // Switching WebView providers is possible only from API >= 24.
@@ -44,19 +49,25 @@ public final class NavigationMenuHelper {
      * This should be called inside {@code Activity#onOptionsItemSelected} method.
      * @return {@code true} if the item selection event is consumed.
      */
-    public static boolean onOptionsItemSelected(Activity activity, MenuItem item) {
+    public static boolean onOptionsItemSelected(FragmentActivity activity, MenuItem item) {
+        Fragment fragment = null;
         if (item.getItemId() == R.id.nav_menu_crash_ui) {
-            activity.startActivity(new Intent(activity, CrashesListActivity.class));
+            fragment = new CrashesListFragment();
         } else if (item.getItemId() == R.id.nav_menu_flags_ui) {
-            activity.startActivity(new Intent(activity, FlagsActivity.class));
+            fragment = new FlagsFragment();
         } else if (item.getItemId() == R.id.nav_menu_main_ui) {
-            activity.startActivity(new Intent(activity, MainActivity.class));
+            fragment = new HomeFragment();
         } else if (item.getItemId() == R.id.nav_menu_switch_provider
                 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
             activity.startActivity(new Intent(Settings.ACTION_WEBVIEW_SETTINGS));
-        } else {
-            return false;
+            return true;
         }
+        if (fragment == null) return false;
+
+        FragmentManager fm = activity.getSupportFragmentManager();
+        FragmentTransaction transaction = fm.beginTransaction();
+        transaction.replace(R.id.content_fragment, fragment);
+        transaction.commit();
         return true;
     }
 

android_webview/nonembedded/java/src/org/chromium/android_webview/services/DeveloperUiService.java

@@ -36,6 +36,12 @@ public final class DeveloperUiService extends Service {
     private static final String CHANNEL_ID = "DevUiChannel";
     private static final int FLAG_OVERRIDE_NOTIFICATION_ID = 1;
 
+    // Keep in sync with MainActivity.java
+    private static final String FRAGMENT_ID_INTENT_EXTRA = "fragment-id";
+    private static final int FRAGMENT_ID_HOME = 0;
+    private static final int FRAGMENT_ID_CRASHES = 1;
+    private static final int FRAGMENT_ID_FLAGS = 2;
+
     private static final Object sLock = new Object();
     @GuardedBy("sLock")
     private static Map<String, Boolean> sOverriddenFlags = new HashMap<>();
@@ -106,7 +112,8 @@ public final class DeveloperUiService extends Service {
 
         Intent notificationIntent = new Intent();
         notificationIntent.setClassName(
-                getPackageName(), "org.chromium.android_webview.devui.FlagsActivity");
+                getPackageName(), "org.chromium.android_webview.devui.MainActivity");
+        notificationIntent.putExtra(FRAGMENT_ID_INTENT_EXTRA, FRAGMENT_ID_FLAGS);
         PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
 
         Notification.Builder builder =

chrome/android/java/monochrome_public_bundle__base_bundle_module.AndroidManifest.expected

@@ -1022,22 +1022,6 @@
           android:name="com.android.settings.PRIMARY_PROFILE_CONTROLLED"
           android:value="true"/>
     </activity>
-    <activity
-        android:label="WebView
-        Crashes"
-        android:launchMode="singleTop"
-        android:name="org.chromium.android_webview.devui.CrashesListActivity"
-        android:process=":webview_apk"
-        android:taskAffinity="org.chromium.chrome.org.chromium.android_webview.devui"
-        android:theme="@style/Theme.DevUi.DayNight"/>
-    <activity
-        android:label="WebView
-        Flags"
-        android:launchMode="singleTop"
-        android:name="org.chromium.android_webview.devui.FlagsActivity"
-        android:process=":webview_apk"
-        android:taskAffinity="org.chromium.chrome.org.chromium.android_webview.devui"
-        android:theme="@style/Theme.DevUi.DayNight"/>
     <activity
         android:enabled="false"
         android:excludeFromRecents="true"