Remove most usages of guava.

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java

 // Copyright 2014 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.tabmodel;
 
-import com.google.common.annotations.VisibleForTesting;
-
+import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.Tab;
 import org.chromium.chrome.browser.profiles.Profile;
 
 /**
  * Singleton class intended to stub out Tab model before it has been created.
  */
 public class EmptyTabModel implements TabModel {
 
     /**
      * Used to mock TabModel. Application code should use getInstance() to construct an
@@ skipping 108 matching lines @@
 
     @Override
     public void addObserver(TabModelObserver observer) {
     }
 
     @Override
     public void removeObserver(TabModelObserver observer) {
     }
 
 }