Remove deprecated class WebContentsObserverAndroid and cleanup existing usages.

content/public/android/java/src/org/chromium/content/browser/WebContentsObserverAndroid.java

Index: content/public/android/java/src/org/chromium/content/browser/WebContentsObserverAndroid.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/WebContentsObserverAndroid.java b/content/public/android/java/src/org/chromium/content/browser/WebContentsObserverAndroid.java
deleted file mode 100644
index 9040fbc998389fb13bc1d80c9627fa8fdca8a4f1..0000000000000000000000000000000000000000
--- a/content/public/android/java/src/org/chromium/content/browser/WebContentsObserverAndroid.java
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2012 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.content.browser;
-
-import org.chromium.content_public.browser.WebContents;
-
-/**
- * @deprecated This class has been renamed to {@link WebContentsObserver} and
- * will be removed when all usages have been removed. See http://crbug.com/3961
- */
-@Deprecated
-public abstract class WebContentsObserverAndroid extends WebContentsObserver {
-
-    public WebContentsObserverAndroid(WebContents webContents) {
-        super(webContents);
-    }
-}