[Android] Fix a flicker in stopping Chrome

chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java

Index: chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
diff --git a/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java b/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
index 97cea993e5ca7c1447a137b4e82cc269621bffc6..6e89d0d1d75f60bb887d50db1c54297477e6b4de 100644
--- a/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
+++ b/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
@@ -95,6 +95,11 @@ public class TabManager extends LinearLayout {
             protected void onReadyToRender() {
                 if (mCurrentTab == null) createTab(mStartupUrl, TabLaunchType.FROM_RESTORE);
             }
+
+            @Override
+            protected void onWindowHidden() {

[David Trainor- moved to gerrit, 2015/01/15 01:16:07]

Can we just override onWindowVisibilityChanged here instead and do this?  Then
we don't have to store the mWindowShown variable and we can just call hide on
GONE.  I don't think two subsequent calls to hide will do anything.

[Changwan Ryu, 2015/01/15 01:51:33]

Done.

+                if (mCurrentTab != null) mCurrentTab.onWindowHidden();
+            }
         };
         mContentViewRenderView.onNativeLibraryLoaded(window);
         mContentViewHolder.addView(mContentViewRenderView,