Android: Factor Tab reparenting job out of Tab

Tab reparenting task is used for custom tab or in multi window mode
to move a Tab object from an activity to another. This CL refactors
it into its own per-tab class to drive the task.

Bug: 995903

Change-Id: I5d9565765902a5669fdd9cb2c3b7439228a53598
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829618
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707160}

chrome/android/BUILD.gn

@@ -2707,6 +2707,7 @@ generate_jni("chrome_jni_headers") {
     "java/src/org/chromium/chrome/browser/tab/TabState.java",
     "java/src/org/chromium/chrome/browser/tab/TabWebContentsDelegateAndroid.java",
     "java/src/org/chromium/chrome/browser/tab/TrustedCdn.java",
+    "java/src/org/chromium/chrome/browser/tab_activity_glue/ReparentingTask.java",
     "java/src/org/chromium/chrome/browser/tabmodel/TabModelJniBridge.java",
     "java/src/org/chromium/chrome/browser/tabmodel/TabModelObserverJniBridge.java",
     "java/src/org/chromium/chrome/browser/toolbar/LocationBarModel.java",

chrome/android/chrome_java_sources.gni

@@ -402,6 +402,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/customtabs/NavigationInfoCaptureTrigger.java",
   "java/src/org/chromium/chrome/browser/customtabs/PageLoadMetricsObserver.java",
   "java/src/org/chromium/chrome/browser/customtabs/PaymentHandlerActivity.java",
+  "java/src/org/chromium/chrome/browser/customtabs/ReparentingTaskProvider.java",
   "java/src/org/chromium/chrome/browser/customtabs/RequestThrottler.java",
   "java/src/org/chromium/chrome/browser/customtabs/SeparateTaskCustomTabActivity.java",
   "java/src/org/chromium/chrome/browser/customtabs/SeparateTaskCustomTabActivity0.java",
@@ -1616,6 +1617,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/tabmodel/document/AsyncTabCreationParams.java",
   "java/src/org/chromium/chrome/browser/tabmodel/document/TabDelegate.java",
   "java/src/org/chromium/chrome/browser/tab_activity_glue/ActivityTabWebContentsDelegateAndroid.java",
+  "java/src/org/chromium/chrome/browser/tab_activity_glue/ReparentingTask.java",
   "java/src/org/chromium/chrome/browser/tab_activity_glue/TabDelegateFactoryImpl.java",
   "java/src/org/chromium/chrome/browser/tasks/ReturnToChromeExperimentsUtil.java",
   "java/src/org/chromium/chrome/browser/tasks/EngagementTimeUtil.java",

chrome/android/java/src/org/chromium/chrome/browser/customtabs/HiddenTabHolder.java

@@ -22,6 +22,7 @@ import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.TabBuilder;
 import org.chromium.chrome.browser.tab.TabObserver;
+import org.chromium.chrome.browser.tab_activity_glue.ReparentingTask;
 import org.chromium.chrome.browser.tabmodel.TabLaunchType;
 import org.chromium.chrome.browser.util.UrlUtilities;
 import org.chromium.content_public.browser.LoadUrlParams;
@@ -126,7 +127,7 @@ public class HiddenTabHolder {
         int width = bounds.right - bounds.left;
         int height = bounds.bottom - bounds.top;
         tab.getWebContents().setSize(width, height);
-        tab.detach();
+        ReparentingTask.detach(tab);
         return tab;
     }
 

chrome/android/java/src/org/chromium/chrome/browser/customtabs/ReparentingTaskProvider.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.chrome.browser.customtabs;
+
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.browser.tab_activity_glue.ReparentingTask;
+
+import javax.inject.Inject;
+
+/**
+ * Provides {@link ReparentingTask} object to CustomTabActivityController.
+ * Makes the target class test-friendly by allowing for mock injection.
+ */
+public class ReparentingTaskProvider {
+    @Inject
+    public ReparentingTaskProvider() {}
+
+    public ReparentingTask get(Tab tab) {
+        return ReparentingTask.from(tab);
+    }
+}

chrome/android/java/src/org/chromium/chrome/browser/customtabs/content/CustomTabActivityTabController.java

@@ -33,6 +33,7 @@ import org.chromium.chrome.browser.customtabs.CustomTabTabPersistencePolicy;
 import org.chromium.chrome.browser.customtabs.CustomTabsConnection;
 import org.chromium.chrome.browser.customtabs.FirstMeaningfulPaintObserver;
 import org.chromium.chrome.browser.customtabs.PageLoadMetricsObserver;
+import org.chromium.chrome.browser.customtabs.ReparentingTaskProvider;
 import org.chromium.chrome.browser.dependency_injection.ActivityScope;
 import org.chromium.chrome.browser.init.StartupTabPreloader;
 import org.chromium.chrome.browser.lifecycle.ActivityLifecycleDispatcher;
@@ -97,6 +98,7 @@ public class CustomTabActivityTabController implements InflationObserver, Native
     private final ActivityTabProvider mActivityTabProvider;
     private final CustomTabActivityTabProvider mTabProvider;
     private final StartupTabPreloader mStartupTabPreloader;
+    private final ReparentingTaskProvider mReparentingTaskProvider;
 
     @Nullable
     private final CustomTabsSessionToken mSession;
@@ -120,7 +122,8 @@ public class CustomTabActivityTabController implements InflationObserver, Native
             CustomTabTabPersistencePolicy persistencePolicy, CustomTabActivityTabFactory tabFactory,
             Lazy<CustomTabObserver> customTabObserver, WebContentsFactory webContentsFactory,
             CustomTabNavigationEventObserver tabNavigationEventObserver,
-            CustomTabActivityTabProvider tabProvider, StartupTabPreloader startupTabPreloader) {
+            CustomTabActivityTabProvider tabProvider, StartupTabPreloader startupTabPreloader,
+            ReparentingTaskProvider reparentingTaskProvider) {
         mCustomTabDelegateFactory = customTabDelegateFactory;
         mActivity = activity;
         mConnection = connection;
@@ -136,6 +139,7 @@ public class CustomTabActivityTabController implements InflationObserver, Native
         mActivityTabProvider = activityTabProvider;
         mTabProvider = tabProvider;
         mStartupTabPreloader = startupTabPreloader;
+        mReparentingTaskProvider = reparentingTaskProvider;
 
         mSession = mIntentDataProvider.getSession();
         mIntent = mIntentDataProvider.getIntent();
@@ -166,7 +170,8 @@ public class CustomTabActivityTabController implements InflationObserver, Native
             return;
         }
         mTabProvider.removeTab();
-        tab.detachAndStartReparenting(intent, startActivityOptions, finishCallback);
+        mReparentingTaskProvider.get(tab).begin(
+                mActivity, intent, startActivityOptions, finishCallback);
     }
 
     /**
@@ -311,7 +316,7 @@ public class CustomTabActivityTabController implements InflationObserver, Native
         if (mode == TabCreationMode.HIDDEN) {
             TabReparentingParams params =
                     (TabReparentingParams) AsyncTabParamsManager.remove(tab.getId());
-            tab.attachAndFinishReparenting(mActivity, mCustomTabDelegateFactory.get(),
+            mReparentingTaskProvider.get(tab).finish(mActivity, mCustomTabDelegateFactory.get(),
                     (params == null ? null : params.getFinalizeCallback()));
         }
 

chrome/android/java/src/org/chromium/chrome/browser/customtabs/dependency_injection/CustomTabActivityComponent.java

@@ -5,14 +5,15 @@
 package org.chromium.chrome.browser.customtabs.dependency_injection;
 
 import org.chromium.chrome.browser.browserservices.trustedwebactivityui.TrustedWebActivityCoordinator;
-import org.chromium.chrome.browser.customtabs.CustomTabActivityClientConnectionKeeper;
 import org.chromium.chrome.browser.browserservices.trustedwebactivityui.TwaFinishHandler;
+import org.chromium.chrome.browser.customtabs.CustomTabActivityClientConnectionKeeper;
 import org.chromium.chrome.browser.customtabs.CustomTabActivityLifecycleUmaTracker;
 import org.chromium.chrome.browser.customtabs.CustomTabBottomBarDelegate;
 import org.chromium.chrome.browser.customtabs.CustomTabCompositorContentInitializer;
 import org.chromium.chrome.browser.customtabs.CustomTabSessionHandler;
 import org.chromium.chrome.browser.customtabs.CustomTabStatusBarColorProvider;
 import org.chromium.chrome.browser.customtabs.CustomTabTabPersistencePolicy;
+import org.chromium.chrome.browser.customtabs.ReparentingTaskProvider;
 import org.chromium.chrome.browser.customtabs.content.CustomTabActivityNavigationController;
 import org.chromium.chrome.browser.customtabs.content.CustomTabActivityTabController;
 import org.chromium.chrome.browser.customtabs.content.CustomTabActivityTabFactory;
@@ -54,5 +55,7 @@ public interface CustomTabActivityComponent extends ChromeActivityComponent {
     TwaFinishHandler resolveTwaFinishHandler();
     ImmersiveModeController resolveImmersiveModeController();
 
-    CustomTabTabPersistencePolicy resolveTabPersistencePolicy(); // For testing
+    // For testing
+    CustomTabTabPersistencePolicy resolveTabPersistencePolicy();
+    ReparentingTaskProvider resolveReparentingTaskProvider();
 }

chrome/android/java/src/org/chromium/chrome/browser/multiwindow/MultiInstanceManager.java

@@ -26,6 +26,7 @@ import org.chromium.chrome.browser.lifecycle.Destroyable;
 import org.chromium.chrome.browser.lifecycle.NativeInitObserver;
 import org.chromium.chrome.browser.lifecycle.PauseResumeWithNativeObserver;
 import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.browser.tab_activity_glue.ReparentingTask;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.chrome.browser.util.AndroidTaskUtils;
 import org.chromium.chrome.browser.util.FeatureUtilities;
@@ -314,7 +315,7 @@ public class MultiInstanceManager
         if (intent == null) return;
 
         onMultiInstanceModeStarted();
-        tab.detachAndStartReparenting(intent,
+        ReparentingTask.from(tab).begin(mContext, intent,
                 mMultiWindowModeStateDispatcher.getOpenInOtherWindowActivityOptions(), null);
     }
 }

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

@@ -7,11 +7,7 @@ package org.chromium.chrome.browser.tab;
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.Context;
-import android.content.Intent;
 import android.graphics.Rect;
-import android.net.Uri;
-import android.os.Bundle;
-import android.provider.Browser;
 import android.text.TextUtils;
 import android.view.View;
 import android.view.View.OnAttachStateChangeListener;
@@ -33,14 +29,11 @@ import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.NativeMethods;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeActivity;
-import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.ChromeVersionInfo;
-import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.WarmupManager;
 import org.chromium.chrome.browser.WebContentsFactory;
 import org.chromium.chrome.browser.content.ContentUtils;
 import org.chromium.chrome.browser.contextmenu.ContextMenuPopulator;
-import org.chromium.chrome.browser.document.ChromeLauncherActivity;
 import org.chromium.chrome.browser.fullscreen.FullscreenOptions;
 import org.chromium.chrome.browser.native_page.FrozenNativePage;
 import org.chromium.chrome.browser.native_page.NativePage;
@@ -55,9 +48,7 @@ import org.chromium.chrome.browser.rlz.RevenueStats;
 import org.chromium.chrome.browser.ssl.SecurityStateModel;
 import org.chromium.chrome.browser.tab.TabState.WebContentsState;
 import org.chromium.chrome.browser.tab.TabUma.TabCreationState;
-import org.chromium.chrome.browser.tabmodel.AsyncTabParamsManager;
 import org.chromium.chrome.browser.tabmodel.TabLaunchType;
-import org.chromium.chrome.browser.tabmodel.TabReparentingParams;
 import org.chromium.chrome.browser.tabmodel.TabSelectionType;
 import org.chromium.chrome.browser.util.UrlConstants;
 import org.chromium.chrome.browser.vr.VrModuleProvider;
@@ -900,125 +891,30 @@ public class Tab {
     }
 
     /**
-     * Begins the tab reparenting process. Detaches the tab from its current activity and fires
-     * an Intent to reparent the tab into its new host activity.
-     *
-     * @param intent An optional intent with the desired component, flags, or extras to use when
-     *               launching the new host activity. This intent's URI and action will be
-     *               overriden. This may be null if no intent customization is needed.
-     * @param startActivityOptions Options to pass to {@link Activity#startActivity(Intent, Bundle)}
-     * @param finalizeCallback A callback that will be called after the tab is attached to the new
-     *                         host activity in {@link #attachAndFinishReparenting}.
-     * @return Whether reparenting succeeded. If false, the tab was not removed and the intent was
-     *         not fired.
-     */
-    public boolean detachAndStartReparenting(Intent intent, Bundle startActivityOptions,
-            Runnable finalizeCallback) {
-        ChromeActivity activity = getActivity();
-        if (activity == null) return false;
-
-        if (intent == null) intent = new Intent();
-        if (intent.getComponent() == null) {
-            intent.setClass(mThemedApplicationContext, ChromeLauncherActivity.class);
-        }
-        intent.setAction(Intent.ACTION_VIEW);
-        if (TextUtils.isEmpty(intent.getDataString())) intent.setData(Uri.parse(getUrl()));
-        if (isIncognito()) {
-            intent.putExtra(Browser.EXTRA_APPLICATION_ID,
-                    ContextUtils.getApplicationContext().getPackageName());
-            intent.putExtra(IntentHandler.EXTRA_OPEN_NEW_INCOGNITO_TAB, true);
-        }
-        IntentHandler.addTrustedIntentExtras(intent);
-
-        if (ChromeFeatureList.isEnabled(ChromeFeatureList.TAB_REPARENTING)) {
-            // Add the tab to AsyncTabParamsManager before removing it from the current model to
-            // ensure the global count of tabs is correct. See https://crbug.com/611806.
-            intent.putExtra(IntentHandler.EXTRA_TAB_ID, mId);
-            AsyncTabParamsManager.add(
-                    mId, new TabReparentingParams(this, intent, finalizeCallback));
-
-            detach();
-        }
-
-        activity.startActivity(intent, startActivityOptions);
-        return true;
-    }
-
-    /**
-     * Detaches a tab from its current activity if any.
-     *
-     * In details, this function:
-     * - Removes the tab from its current {@link TabModelSelector}, effectively severing
-     *   the {@link Activity} to {@link Tab} link.
-     */
-    public void detach() {
-        // TODO(yusufo): We can't call updateWindowAndroid here and set mWindowAndroid to null
-        // because many code paths (including navigation) expect the tab to always be associated
-        // with an activity, and will crash. crbug.com/657007
-        WebContents webContents = getWebContents();
-        if (webContents != null) webContents.setTopLevelNativeWindow(null);
-
-        // TabModelSelector of this Tab, if present, gets notified to remove the tab from
-        // the TabModel it belonged to.
-        for (TabObserver observer : mObservers) {
-            observer.onActivityAttachmentChanged(this, false);
-        }
-    }
-
-    /**
-     * Finishes the tab reparenting process. Attaches the tab to the new activity, and updates the
-     * tab and related objects to reference the new activity. This updates many delegates inside the
-     * tab and {@link WebContents} both on java and native sides.
-     *
-     * @param activity The new activity this tab should be associated with.
-     * @param tabDelegateFactory The new delegate factory this tab should be using.
-     * @param finalizeCallback A Callback to be called after the Tab has been reparented.
-     */
-    public void attachAndFinishReparenting(ChromeActivity activity,
-            TabDelegateFactory tabDelegateFactory,
-            @Nullable Runnable finalizeCallback) {
-        // TODO(yusufo): Share these calls with the construction related calls.
-        // crbug.com/590281
-        activity.getCompositorViewHolder().prepareForTabReparenting();
-
-        attach(activity, tabDelegateFactory);
-
-        mIsTabStateDirty = true;
-
-        if (finalizeCallback != null) finalizeCallback.run();
-    }
-
-    /**
-     * Attaches the tab to the new activity and updates the tab and related objects to reference the
-     * new activity. This updates many delegates inside the tab and {@link WebContents} both on
-     * java and native sides.
-     * TODO(ltian:) explore calling this for all types of tabs.
-     *
-     * @param activity  The new activity this tab should be associated with.
-     * @param tabDelegateFactory  The new delegate factory this tab should be using.
+     * Set {@link TabDelegateFactory} instance and updates the references.
+     * @param factory TabDelegateFactory instance.
      */
-    public void attach(ChromeActivity activity, TabDelegateFactory tabDelegateFactory) {
-        assert isDetached();
-        updateWindowAndroid(activity.getWindowAndroid());
-
+    public void setDelegateFactory(TabDelegateFactory factory) {
         // Update the delegate factory, then recreate and propagate all delegates.
-        mDelegateFactory = tabDelegateFactory;
-        mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);
-
-        // Reload the NativePage (if any), since the old NativePage has a reference to the old
-        // activity.
-        maybeShowNativePage(getUrl(), true);
+        mDelegateFactory = factory;
 
-        assert mNativeTabAndroid != 0;
-        TabJni.get().attachDetachedTab(mNativeTabAndroid, Tab.this);
+        mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);
 
         if (getWebContents() != null) {
             TabJni.get().updateDelegates(mNativeTabAndroid, Tab.this, mWebContentsDelegate,
                     new TabContextMenuPopulator(
                             mDelegateFactory.createContextMenuPopulator(this), this));
         }
+    }
 
-        for (TabObserver observer : mObservers) observer.onActivityAttachmentChanged(this, true);
+    /**
+     * Notify observers of the new attachment state to activity.
+     * @param attached {@code true} if the tab gets attached.
+     */
+    public void notifyActivityAttachmentChanged(boolean attached) {
+        for (TabObserver observer : mObservers) {
+            observer.onActivityAttachmentChanged(this, attached);
+        }
     }
 
     /**
@@ -1037,15 +933,16 @@ public class Tab {
     }
 
     /**
+     * @param tab {@link Tab} instance being checked.
      * @return Whether the tab is detached from any Activity and its {@link WindowAndroid}.
      * Certain functionalities will not work until it is attached to an activity
-     * with {@link Tab#attachAndFinishReparenting}.
+     * with {@link ReparentingTask#finish}.
      */
-    public boolean isDetached() {
-        if (getWebContents() == null) return true;
+    public static boolean isDetached(Tab tab) {
+        if (tab.getWebContents() == null) return true;
         // Should get WindowAndroid from WebContents since the one from |getWindowAndroid()|
         // is always non-null even when the tab is in detached state. See the comment in |detach()|.
-        WindowAndroid window = getWebContents().getTopLevelNativeWindow();
+        WindowAndroid window = tab.getWebContents().getTopLevelNativeWindow();
         if (window == null) return true;
         Activity activity = ContextUtils.activityFromContext(window.getContext().get());
         return !(activity instanceof ChromeActivity);
@@ -1170,7 +1067,7 @@ public class Tab {
             mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);
 
             assert mNativeTabAndroid != 0;
-            TabJni.get().initWebContents(mNativeTabAndroid, Tab.this, mIncognito, isDetached(),
+            TabJni.get().initWebContents(mNativeTabAndroid, Tab.this, mIncognito, isDetached(this),
                     webContents, mSourceTabId, mWebContentsDelegate,
                     new TabContextMenuPopulator(
                             mDelegateFactory.createContextMenuPopulator(this), this));
@@ -1194,11 +1091,11 @@ public class Tab {
      *                    matches the URL.
      * @return True, if a native page was displayed for url.
      */
-    boolean maybeShowNativePage(String url, boolean forceReload) {
+    public boolean maybeShowNativePage(String url, boolean forceReload) {
         // While detached for reparenting we don't have an owning Activity, or TabModelSelector,
         // so we can't create the native page. The native page will be created once reparenting is
         // completed.
-        if (isDetached()) return false;
+        if (isDetached(this)) return false;
         NativePage candidateForReuse = forceReload ? null : getNativePage();
         NativePage nativePage = NativePageFactory.createNativePageForURL(
                 url, candidateForReuse, this, getActivity());
@@ -1883,6 +1780,5 @@ public class Tab {
         void setActiveNavigationEntryTitleForUrl(
                 long nativeTabAndroid, Tab caller, String url, String title);
         void loadOriginalImage(long nativeTabAndroid, Tab caller);
-        void attachDetachedTab(long nativeTabAndroid, Tab caller);
     }
 }

chrome/android/java/src/org/chromium/chrome/browser/tab_activity_glue/ReparentingTask.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.chrome.browser.tab_activity_glue;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Bundle;
+import android.provider.Browser;
+import android.text.TextUtils;
+
+import androidx.annotation.Nullable;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.UserData;
+import org.chromium.base.annotations.NativeMethods;
+import org.chromium.chrome.browser.ChromeActivity;
+import org.chromium.chrome.browser.ChromeFeatureList;
+import org.chromium.chrome.browser.IntentHandler;
+import org.chromium.chrome.browser.document.ChromeLauncherActivity;
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.browser.tab.TabDelegateFactory;
+import org.chromium.chrome.browser.tabmodel.AsyncTabParamsManager;
+import org.chromium.chrome.browser.tabmodel.TabReparentingParams;
+import org.chromium.content_public.browser.WebContents;
+import org.chromium.ui.base.WindowAndroid;
+
+/**
+ * Takes care of reparenting a Tab object from one Activity to another.
+ */
+public class ReparentingTask implements UserData {
+    private static final Class<ReparentingTask> USER_DATA_KEY = ReparentingTask.class;
+
+    private final Tab mTab;
+
+    /**
+     * @param tab {@link Tab} object.
+     * @return {@link ReparentingTask} object for a given {@link Tab}. Creates one
+     *         if not present.
+     */
+    public static ReparentingTask from(Tab tab) {
+        ReparentingTask reparentingTask = get(tab);
+        if (reparentingTask == null) {
+            reparentingTask =
+                    tab.getUserDataHost().setUserData(USER_DATA_KEY, new ReparentingTask(tab));
+        }
+        return reparentingTask;
+    }
+
+    @Nullable
+    private static ReparentingTask get(Tab tab) {
+        return tab.getUserDataHost().getUserData(USER_DATA_KEY);
+    }
+
+    private ReparentingTask(Tab tab) {
+        mTab = tab;
+    }
+
+    /**
+     * Begins the tab reparenting process. Detaches the tab from its current activity and fires
+     * an Intent to reparent the tab into its new host activity.
+     *
+     * @param context {@link Context} object used to start a new activity.
+     * @param intent An optional intent with the desired component, flags, or extras to use when
+     *               launching the new host activity. This intent's URI and action will be
+     *               overridden. This may be null if no intent customization is needed.
+     * @param startActivityOptions Options to pass to {@link Activity#startActivity(Intent, Bundle)}
+     * @param finalizeCallback A callback that will be called after the tab is attached to the new
+     *                         host activity in {@link #attachAndFinishReparenting}.
+     * @return Whether reparenting succeeded. If false, the tab was not removed and the intent was
+     *         not fired.
+     */
+    public boolean begin(Context context, Intent intent, Bundle startActivityOptions,
+            Runnable finalizeCallback) {
+        if (intent == null) intent = new Intent();
+        if (intent.getComponent() == null) {
+            intent.setClass(mTab.getThemedApplicationContext(), ChromeLauncherActivity.class);
+        }
+        intent.setAction(Intent.ACTION_VIEW);
+        if (TextUtils.isEmpty(intent.getDataString())) intent.setData(Uri.parse(mTab.getUrl()));
+        if (mTab.isIncognito()) {
+            intent.putExtra(Browser.EXTRA_APPLICATION_ID,
+                    ContextUtils.getApplicationContext().getPackageName());
+            intent.putExtra(IntentHandler.EXTRA_OPEN_NEW_INCOGNITO_TAB, true);
+        }
+        IntentHandler.addTrustedIntentExtras(intent);
+
+        if (ChromeFeatureList.isEnabled(ChromeFeatureList.TAB_REPARENTING)) {
+            // Add the tab to AsyncTabParamsManager before removing it from the current model to
+            // ensure the global count of tabs is correct. See https://crbug.com/611806.
+            intent.putExtra(IntentHandler.EXTRA_TAB_ID, mTab.getId());
+            AsyncTabParamsManager.add(
+                    mTab.getId(), new TabReparentingParams(mTab, intent, finalizeCallback));
+
+            detach(mTab);
+        }
+
+        context.startActivity(intent, startActivityOptions);
+        return true;
+    }
+
+    /**
+     * Detaches a tab from its current activity if any.
+     *
+     * In details, this function:
+     * - Removes the tab from its current {@link TabModelSelector}, effectively severing
+     *   the {@link Activity} to {@link Tab} link.
+     */
+    public static void detach(Tab tab) {
+        // TODO(yusufo): We can't call tab.updateWindowAndroid that sets |mWindowAndroid| to null
+        // because many code paths (including navigation) expect the tab to always be associated
+        // with an activity, and will crash. crbug.com/657007
+        WebContents webContents = tab.getWebContents();
+        if (webContents != null) webContents.setTopLevelNativeWindow(null);
+
+        // TabModelSelector of this Tab, if present, gets notified to remove the tab from
+        // the TabModel it belonged to.
+        tab.notifyActivityAttachmentChanged(false);
+    }
+
+    /**
+     * Finishes the tab reparenting process. Attaches this tab to a new activity, and updates
+     * the tab and related objects to reference it. This updates many delegates inside the tab
+     * and {@link WebContents} both on java and native sides.
+     *
+     * @param activity A new {@link ChromeActivity} to attach this Tab instance to.
+     * @param tabDelegateFactory The new delegate factory this tab should be using.
+     * @param finalizeCallback A Callback to be called after the Tab has been reparented.
+     */
+    public void finish(ChromeActivity activity, TabDelegateFactory tabDelegateFactory,
+            @Nullable Runnable finalizeCallback) {
+        activity.getCompositorViewHolder().prepareForTabReparenting();
+        attach(activity.getWindowAndroid(), tabDelegateFactory);
+        mTab.setIsTabStateDirty(true);
+        if (finalizeCallback != null) finalizeCallback.run();
+    }
+
+    /**
+     * Attaches the tab to the new activity and updates the tab and related objects to reference the
+     * new activity. This updates many delegates inside the tab and {@link WebContents} both on
+     * java and native sides.
+     *
+     * @param window A new {@link WindowAndroid} to attach the tab to.
+     * @param activity  The new activity this tab should be associated with.
+     * @param tabDelegateFactory  The new delegate factory this tab should be using.
+     */
+    private void attach(WindowAndroid window, TabDelegateFactory tabDelegateFactory) {
+        assert Tab.isDetached(mTab);
+        mTab.updateWindowAndroid(window);
+        mTab.setDelegateFactory(tabDelegateFactory);
+
+        // Reload the NativePage (if any), since the old NativePage has a reference to the old
+        // activity.
+        mTab.maybeShowNativePage(mTab.getUrl(), true);
+
+        ReparentingTaskJni.get().attachTab(mTab.getWebContents());
+        mTab.notifyActivityAttachmentChanged(true);
+    }
+
+    @NativeMethods
+    interface Natives {
+        void attachTab(WebContents webContents);
+    }
+}

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/ChromeTabCreator.java

@@ -23,6 +23,7 @@ import org.chromium.chrome.browser.tab.TabDelegateFactory;
 import org.chromium.chrome.browser.tab.TabParentIntent;
 import org.chromium.chrome.browser.tab.TabRedirectHandler;
 import org.chromium.chrome.browser.tab.TabState;
+import org.chromium.chrome.browser.tab_activity_glue.ReparentingTask;
 import org.chromium.chrome.browser.tab_activity_glue.TabDelegateFactoryImpl;
 import org.chromium.chrome.browser.util.IntentUtils;
 import org.chromium.components.url_formatter.UrlFormatter;
@@ -122,7 +123,7 @@ public class ChromeTabCreator extends TabCreatorManager.TabCreator {
 
                 TabReparentingParams params = (TabReparentingParams) asyncParams;
                 tab = params.getTabToReparent();
-                tab.attachAndFinishReparenting(
+                ReparentingTask.from(tab).finish(
                         mActivity, createDefaultTabDelegateFactory(), params.getFinalizeCallback());
             } else if (asyncParams != null && asyncParams.getWebContents() != null) {
                 openInForeground = true;

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelSelectorImpl.java

@@ -330,7 +330,7 @@ public class TabModelSelectorImpl extends TabModelSelectorBase implements TabMod
             TabModelImpl.startTabSwitchLatencyTiming(type);
         }
         if (mVisibleTab != null && mVisibleTab != tab && !mVisibleTab.needsReload()) {
-            if (mVisibleTab.isInitialized() && !mVisibleTab.isDetached()) {
+            if (mVisibleTab.isInitialized() && !Tab.isDetached(mVisibleTab)) {
                 // TODO(dtrainor): Once we figure out why we can't grab a snapshot from the current
                 // tab when we have other tabs loading from external apps remove the checks for
                 // FROM_EXTERNAL_APP/FROM_NEW.

chrome/android/junit/src/org/chromium/chrome/browser/customtabs/content/CustomTabActivityContentTestEnvironment.java

@@ -42,6 +42,7 @@ import org.chromium.chrome.browser.customtabs.CustomTabNavigationEventObserver;
 import org.chromium.chrome.browser.customtabs.CustomTabObserver;
 import org.chromium.chrome.browser.customtabs.CustomTabTabPersistencePolicy;
 import org.chromium.chrome.browser.customtabs.CustomTabsConnection;
+import org.chromium.chrome.browser.customtabs.ReparentingTaskProvider;
 import org.chromium.chrome.browser.customtabs.shadows.ShadowExternalNavigationDelegateImpl;
 import org.chromium.chrome.browser.fullscreen.ChromeFullscreenManager;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
@@ -49,6 +50,7 @@ import org.chromium.chrome.browser.init.StartupTabPreloader;
 import org.chromium.chrome.browser.lifecycle.ActivityLifecycleDispatcher;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.TabObserverRegistrar;
+import org.chromium.chrome.browser.tab_activity_glue.ReparentingTask;
 import org.chromium.chrome.browser.tabmodel.AsyncTabParamsManager;
 import org.chromium.chrome.browser.tabmodel.TabModel;
 import org.chromium.chrome.browser.tabmodel.TabModelSelectorImpl;
@@ -69,6 +71,7 @@ public class CustomTabActivityContentTestEnvironment extends TestWatcher {
 
     public final Intent intent = new Intent();
 
+    // clang-format off
     @Mock public CustomTabDelegateFactory customTabDelegateFactory;
     @Mock public ChromeActivity activity;
     @Mock public CustomTabsConnection connection;
@@ -85,13 +88,16 @@ public class CustomTabActivityContentTestEnvironment extends TestWatcher {
     @Mock public CustomTabsSessionToken session;
     @Mock public TabModelSelectorImpl tabModelSelector;
     @Mock public TabModel tabModel;
+    @Mock public ReparentingTaskProvider reparentingTaskProvider;
+    @Mock public ReparentingTask reparentingTask;
     @Mock public CustomTabNavigationEventObserver navigationEventObserver;
     @Mock public CloseButtonNavigator closeButtonNavigator;
     @Mock public ToolbarManager toolbarManager;
     @Mock public ChromeBrowserInitializer browserInitializer;
     @Mock public ChromeFullscreenManager fullscreenManager;
-    @Mock
-    public StartupTabPreloader startupTabPreloader;
+    @Mock public StartupTabPreloader startupTabPreloader;
+    // clang-format on
+
     public final CustomTabActivityTabProvider tabProvider = new CustomTabActivityTabProvider();
 
     @Captor public ArgumentCaptor<ActivityTabObserver> activityTabObserverCaptor;
@@ -121,7 +127,7 @@ public class CustomTabActivityContentTestEnvironment extends TestWatcher {
         when(toolbarManager.back()).thenReturn(null);
 
         when(startupTabPreloader.takeTabIfMatchingOrDestroy(any(), anyInt())).thenReturn(null);
-
+        when(reparentingTaskProvider.get(any())).thenReturn(reparentingTask);
         doNothing().when(activityTabProvider).addObserverAndTrigger(
                 activityTabObserverCaptor.capture());
     }
@@ -134,18 +140,15 @@ public class CustomTabActivityContentTestEnvironment extends TestWatcher {
         ShadowExternalNavigationDelegateImpl.setWillChromeHandleIntent(false);
     }
 
+    // clang-format off
     public CustomTabActivityTabController createTabController() {
-        return new CustomTabActivityTabController(activity,
-                ()
-                        -> customTabDelegateFactory,
+        return new CustomTabActivityTabController(activity, () -> customTabDelegateFactory,
                 connection, intentDataProvider, activityTabProvider, tabObserverRegistrar,
-                ()
-                        -> compositorViewHolder,
-                lifecycleDispatcher, warmupManager, tabPersistencePolicy, tabFactory,
-                ()
-                        -> customTabObserver,
-                webContentsFactory, navigationEventObserver, tabProvider, startupTabPreloader);
+                () -> compositorViewHolder, lifecycleDispatcher, warmupManager,
+                tabPersistencePolicy, tabFactory, () -> customTabObserver, webContentsFactory,
+                navigationEventObserver, tabProvider, startupTabPreloader, reparentingTaskProvider);
     }
+    // clang-format on
 
     public CustomTabActivityNavigationController createNavigationController(
             CustomTabActivityTabController tabController) {

chrome/android/junit/src/org/chromium/chrome/browser/customtabs/content/CustomTabActivityTabControllerTest.java

@@ -126,7 +126,7 @@ public class CustomTabActivityTabControllerTest {
     public void finishesReparentingHiddenTab() {
         Tab hiddenTab = env.prepareHiddenTab();
         env.reachNativeInit(mTabController);
-        verify(hiddenTab).attachAndFinishReparenting(any(), any(), any());
+        verify(env.reparentingTaskProvider.get(hiddenTab)).finish(any(), any(), any());
     }
 
     @Test

chrome/browser/BUILD.gn

@@ -2530,6 +2530,7 @@ jumbo_static_library("browser") {
       "android/rappor/rappor_service_bridge.cc",
       "android/recently_closed_tabs_bridge.cc",
       "android/recently_closed_tabs_bridge.h",
+      "android/reparenting_task.cc",
       "android/resource_id.h",
       "android/resource_mapper.cc",
       "android/resource_mapper.h",

chrome/browser/android/reparenting_task.cc

+// 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.
+
+#include "chrome/android/chrome_jni_headers/ReparentingTask_jni.h"
+#include "chrome/browser/android/background_tab_manager.h"
+#include "chrome/browser/history/history_service_factory.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/web_contents.h"
+
+using base::android::JavaParamRef;
+using chrome::android::BackgroundTabManager;
+using content::WebContents;
+
+static void JNI_ReparentingTask_AttachTab(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& jweb_contents) {
+  auto* background_tab_manager = BackgroundTabManager::GetInstance();
+  auto* web_contents = content::WebContents::FromJavaWebContents(jweb_contents);
+  if (background_tab_manager->IsBackgroundTab(web_contents)) {
+    Profile* profile = background_tab_manager->GetProfile();
+    background_tab_manager->CommitHistory(HistoryServiceFactory::GetForProfile(
+        profile, ServiceAccessType::IMPLICIT_ACCESS));
+    background_tab_manager->UnregisterBackgroundTab();
+  }
+}

chrome/browser/android/tab_android.cc

@@ -440,19 +440,6 @@ void TabAndroid::LoadOriginalImage(JNIEnv* env,
   renderer->RequestReloadImageForContextNode();
 }
 
-void TabAndroid::AttachDetachedTab(
-    JNIEnv* env,
-    const base::android::JavaParamRef<jobject>& obj) {
-  BackgroundTabManager* background_tab_manager =
-      BackgroundTabManager::GetInstance();
-  if (background_tab_manager->IsBackgroundTab(web_contents())) {
-    Profile* profile = background_tab_manager->GetProfile();
-    background_tab_manager->CommitHistory(HistoryServiceFactory::GetForProfile(
-        profile, ServiceAccessType::IMPLICIT_ACCESS));
-    background_tab_manager->UnregisterBackgroundTab();
-  }
-}
-
 scoped_refptr<content::DevToolsAgentHost> TabAndroid::GetDevToolsAgentHost() {
   return devtools_host_;
 }

chrome/browser/android/tab_android.h

@@ -173,8 +173,6 @@ class TabAndroid {
 
   void SetDevToolsAgentHost(scoped_refptr<content::DevToolsAgentHost> host);
 
-  void AttachDetachedTab(JNIEnv* env,
-                         const base::android::JavaParamRef<jobject>& obj);
  private:
   JavaObjectWeakGlobalRef weak_java_tab_;