Add tab reparenting

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

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
index 33b3ad40e8f7409be087937f66a876725f9d6e14..de358d94b8e1cf1d129b6e0a5fe121d566e48527 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
@@ -153,7 +153,7 @@ public final class Tab implements ViewGroup.OnHierarchyChangeListener,
     private final Context mThemedApplicationContext;
 
     /** Gives {@link Tab} a way to interact with the Android window. */
-    private final WindowAndroid mWindowAndroid;
+    private WindowAndroid mWindowAndroid;
 
     /** Whether or not this {@link Tab} is initialized and should be interacted with. */
     private boolean mIsInitialized;
@@ -1355,6 +1355,38 @@ public final class Tab implements ViewGroup.OnHierarchyChangeListener,
     }
 
     /**
+     * Detaches tab and related objects from an existing activity and attaches to a new one. This
+     * updates many delegates inside the tab and {@link ContentViewCore} 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.
+     */
+    public void reparentToActivity(ChromeActivity activity, TabDelegateFactory tabDelegateFactory) {
+        ChromeActivity oldActivity = getActivity();
+
+        // Update and propagate for the new WindowAndroid.
+        mWindowAndroid = activity.getWindowAndroid();
+        mContentViewCore.updateWindowAndroid(mWindowAndroid);
+
+        // Update for the controllers that need the Compositor from the new Activity.
+        nativeAttachToTabContentManager(mNativeTabAndroid, activity.getTabContentManager());
+        mFullscreenManager = activity.getFullscreenManager();
+        activity.getCompositorViewHolder().onActiveTabReparented();
+
+        // Update the delegate factory, then recreate and propagate all delegates.
+        mDelegateFactory = tabDelegateFactory;
+        mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);

[Ted C, 2016/02/25 20:05:22]

can the bulk of this method be shared w/ the default construction path?  I would
be nice to make sure things don't diverge and have one way of handling clearing
old state if needed, etc.., etc...

[Yusuf, 2016/02/25 23:05:00]

No?.... :S I mean yes, but it gets so hairy that becomes a pretty large change.
WindowAndroid is in constructor. AttachingTabContentManager is initialize.
FullscreenManager has an individual setter. Delegates are all in
setContentViewCore which gets called multiple times possibly, but is also in
initialize. Then two of the delegates are initialized as a part of
initWebContents. We can call the new one there except for the new one we don't
set the progress to 0.

TODO?

+        nativeUpdateDelegates(mNativeTabAndroid,
+                mWebContentsDelegate, mDelegateFactory.createContextMenuPopulator(this));
+        mTopControlsVisibilityDelegate = mDelegateFactory.createTopControlsVisibilityDelegate(this);
+        setInterceptNavigationDelegate(mDelegateFactory.createInterceptNavigationDelegate(this));
+        mAppBannerManager = mDelegateFactory.createAppBannerManager(this);
+
+        // Take down the old activity, which destroys all the remaining tabmodels and tabs.
+        if (oldActivity != null && !oldActivity.isActivityDestroyed()) oldActivity.finish();

[Ted C, 2016/02/25 20:05:22]

this is...umm...scary.

I don't think this is where this should be done.

If anything, I think the other activity should be able to add a callback to the
asynctabparams and be notified when it is consumed.

[Yusuf, 2016/02/25 23:05:00]

Done.

+    }
+
+    /**
      * @return The delegate factory for testing purposes only.
      */
     public TabDelegateFactory getDelegateFactory() {
@@ -2945,6 +2977,8 @@ public final class Tab implements ViewGroup.OnHierarchyChangeListener,
     private native void nativeInitWebContents(long nativeTabAndroid, boolean incognito,
             ContentViewCore contentViewCore, TabWebContentsDelegateAndroid delegate,
             ContextMenuPopulator contextMenuPopulator);
+    private native void nativeUpdateDelegates(long nativeTabAndroid,
+            TabWebContentsDelegateAndroid delegate, ContextMenuPopulator contextMenuPopulator);
     private native void nativeDestroyWebContents(long nativeTabAndroid, boolean deleteNative);
     private native Profile nativeGetProfileAndroid(long nativeTabAndroid);
     private native int nativeLoadUrl(long nativeTabAndroid, String url, String extraHeaders,