Upstream oodles of Chrome for Android code into Chromium.

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

+// 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() {}
+}