Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/layouts/EmptyOverviewModeObserver.java

Index: chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/layouts/EmptyOverviewModeObserver.java
diff --git a/chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/layouts/EmptyOverviewModeObserver.java b/chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/layouts/EmptyOverviewModeObserver.java
new file mode 100644
index 0000000000000000000000000000000000000000..9f362fca3f31022110f12dd9e3a5658df342e556
--- /dev/null
+++ b/chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/layouts/EmptyOverviewModeObserver.java
@@ -0,0 +1,24 @@
+// Copyright 2015 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.compositor.layouts;
+
+import org.chromium.chrome.browser.compositor.layouts.OverviewModeBehavior.OverviewModeObserver;
+
+/**
+* An empty implementation of {@link OverviewModeObserver}.
+*/
+public class EmptyOverviewModeObserver implements OverviewModeObserver {
+    @Override
+    public void onOverviewModeStartedShowing(boolean showToolbar) {}
+
+    @Override
+    public void onOverviewModeFinishedShowing() {}
+
+    @Override
+    public void onOverviewModeStartedHiding(boolean showToolbar, boolean delayAnimation) {}
+
+    @Override
+    public void onOverviewModeFinishedHiding() {}
+}