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

android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java

Index: android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java b/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
index c3c381a6bd341a6fe3ed36f069f0ac4c37bbf15c..cd45eadac207970cd231f41ca47431fa01edc3c3 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
@@ -13,12 +13,17 @@ import org.chromium.net.NetError;
  */
 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();
@@ -67,4 +72,15 @@ public class AwWebContentsObserver extends WebContentsObserver {
     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;
+    }
 }