Remove DocumentTabObserver and merge task description updates

chrome/android/java/src/org/chromium/chrome/browser/tab/EmptyTabObserver.java

 // Copyright 2013 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.tab;
 
+import android.graphics.Bitmap;
 import android.view.ContextMenu;
 
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.browser.WebContents;
 
 /**
  * An implementation of the {@link TabObserver} which has empty implementations of all methods.
  */
 public class EmptyTabObserver implements TabObserver {
@@ skipping 25 matching lines @@
     @Override
     public void onPageLoadStarted(Tab tab, String url) { }
 
     @Override
     public void onPageLoadFinished(Tab tab) { }
 
     @Override
     public void onPageLoadFailed(Tab tab, int errorCode) { }
 
     @Override
-    public void onFaviconUpdated(Tab tab) { }
+    public void onFaviconUpdated(Tab tab, Bitmap icon) { }
 
     @Override
     public void onTitleUpdated(Tab tab) { }
 
     @Override
     public void onUrlUpdated(Tab tab) { }
 
     @Override
     public void onSSLStateUpdated(Tab tab) { }
 
@@ skipping 59 matching lines @@
     @Override
     public void onDidStartNavigationToPendingEntry(Tab tab, String url) { }
 
     @Override
     public void onBackgroundColorChanged(Tab tab, int color) { }
 
     @Override
     public void webContentsCreated(Tab tab, WebContents sourceWebContents, long openerRenderFrameId,
             String frameName, String targetUrl, WebContents newWebContents) { }
 }