Implement OverlayPanels as SceneOverlays

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java
index 0266a941f5401a17c1af04faee530d48e8061dd1..621440a6f88cfd675256fd3d4851ebe3591955bc 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/Layout.java
@@ -1081,6 +1081,22 @@ public abstract class Layout implements TabContentManager.ThumbnailChangeListene
     }
 
     /**
+     * @return True if a SceneOverlay is handling the creation of a tab.
+     */
+    public boolean isTabCreatingIntercepted() {

[pedro (no code reviews), 2016/04/22 02:11:05]

Looks like this method is identical to the handlesTabCreating() above. Why do we
need this method? 

[mdjones, 2016/04/22 17:03:42]

Another hold-over. This was originally created in this CL; I instead created a
separate  CL https://codereview.chromium.org/1738803004 that already merged. The
name was changed and I forgot to remove this.

+        if (mLayoutTabs == null || mLayoutTabs.length != 1) return false;
+        for (int i = 0; i < mSceneOverlays.size(); i++) {
+            if (mSceneOverlays.get(i).handlesTabCreating()) {
+                // Prevent animation from happening if the overlay handles creation.
+                startHiding(mLayoutTabs[0].getId(), false);
+                doneHiding();
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
      * @return Whether the layout is handling the model updates when closing all the tabs.
      */
     public boolean handlesCloseAll() {