Add tab reparenting

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
index ed00ff56ff0afa72a2135bd35059470938dca441..cfbc36bbe972503852d4a336ac4b4fc89e52185d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
@@ -104,6 +104,7 @@ import org.chromium.chrome.browser.snackbar.SnackbarManager.SnackbarManageable;
 import org.chromium.chrome.browser.sync.ProfileSyncService;
 import org.chromium.chrome.browser.sync.SyncController;
 import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.browser.tabmodel.AsyncTabParamsManager;
 import org.chromium.chrome.browser.tabmodel.ChromeTabCreator;
 import org.chromium.chrome.browser.tabmodel.EmptyTabModel;
 import org.chromium.chrome.browser.tabmodel.TabCreatorManager;
@@ -697,6 +698,9 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
 
     @Override
     public void onStart() {
+        if (mCompositorViewHolder != null && AsyncTabParamsManager.hasParamsWithTabToReparent()) {

[Ted C, 2016/02/25 20:05:21]

Looking at the code, it isn't possible for this to be null.

mCompositorViewHolder is set in setContentView, which is final.  And it is
called from AsyncInitializationActivity#onCreate.

I think all the null checks within this file must be carried over from before
all converging on using the compositor.

Let's buck the trend and not add another!  :-)

[Yusuf, 2016/02/25 23:04:59]

Done.

+            mCompositorViewHolder.onActiveTabReparented();
+        }
         super.onStart();
         if (mContextReporter != null) mContextReporter.enable();