[Android] Add proxy for Java-based WebContentsObservers

android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.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.android_webview;
 
-import org.chromium.content.browser.WebContentsObserver;
 import org.chromium.content_public.browser.WebContents;
+import org.chromium.content_public.browser.WebContentsObserver;
 import org.chromium.net.NetError;
 
 /**
  * Routes notifications from WebContents to AwContentsClient and other listeners.
  */
 public class AwWebContentsObserver extends WebContentsObserver {
     private final AwContentsClient mAwContentsClient;
 
     public AwWebContentsObserver(WebContents webContents, AwContentsClient awContentsClient) {
         super(webContents);
@@ skipping 42 matching lines @@
         if (isFragmentNavigation) {
             mAwContentsClient.onPageFinished(url);
         }
     }
 
     @Override
     public void didNavigateAnyFrame(String url, String baseUrl, boolean isReload) {
         mAwContentsClient.doUpdateVisitedHistory(url, isReload);
     }
 }