[Android WebView] Synthesize a fake page loading event on page source modification (Re-land)

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.net.NetError;
 
 /**
  * Routes notifications from WebContents to AwContentsClient and other listeners.
  */
 public class AwWebContentsObserver extends WebContentsObserver {
     private final AwContentsClient mAwContentsClient;
+    private boolean mHasStartedAnyProvisionalLoad = false;
 
     public AwWebContentsObserver(WebContents webContents, AwContentsClient awContentsClient) {
         super(webContents);
         mAwContentsClient = awContentsClient;
     }
 
+    boolean hasStartedAnyProvisionalLoad() {
+        return mHasStartedAnyProvisionalLoad;
+    }
+
     @Override
     public void didFinishLoad(long frameId, String validatedUrl, boolean isMainFrame) {
         String unreachableWebDataUrl = AwContentsStatics.getUnreachableWebDataUrl();
         boolean isErrorUrl =
                 unreachableWebDataUrl != null && unreachableWebDataUrl.equals(validatedUrl);
         if (isMainFrame && !isErrorUrl) {
             mAwContentsClient.onPageFinished(validatedUrl);
         }
     }
 
@@ skipping 28 matching lines @@
         // navigations where only the hash fragment changes.
         if (isFragmentNavigation) {
             mAwContentsClient.onPageFinished(url);
         }
     }
 
     @Override
     public void didNavigateAnyFrame(String url, String baseUrl, boolean isReload) {
         mAwContentsClient.doUpdateVisitedHistory(url, isReload);
     }
+
+    @Override
+    public void didStartProvisionalLoadForFrame(
+            long frameId,
+            long parentFrameId,
+            boolean isMainFrame,
+            String validatedUrl,
+            boolean isErrorPage,
+            boolean isIframeSrcdoc) {
+        mHasStartedAnyProvisionalLoad = true;
+    }
 }