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

android_webview/java/src/org/chromium/android_webview/AwWebContentsDelegateAdapter.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.android_webview;
 
 import android.content.ContentResolver;
 import android.content.Context;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Handler;
 import android.os.Message;
 import android.provider.MediaStore;
+import android.text.TextUtils;
 import android.util.Log;
 import android.view.KeyEvent;
 import android.view.View;
 import android.webkit.ConsoleMessage;
 import android.webkit.ValueCallback;
 
 import org.chromium.base.ContentUriUtils;
 import org.chromium.base.ThreadUtils;
+import org.chromium.content_public.browser.InvalidateTypes;
 
 /**
  * Adapts the AwWebContentsDelegate interface to the AwContentsClient interface.
  * This class also serves a secondary function of routing certain callbacks from the content layer
  * to specific listener interfaces.
  */
 class AwWebContentsDelegateAdapter extends AwWebContentsDelegate {
     private static final String TAG = "AwWebContentsDelegateAdapter";
 
     private final AwContents mAwContents;
@@ skipping 174 matching lines @@
     public boolean addNewContents(boolean isDialog, boolean isUserGesture) {
         return mContentsClient.onCreateWindow(isDialog, isUserGesture);
     }
 
     @Override
     public void activateContents() {
         mContentsClient.onRequestFocus();
     }
 
     @Override
+    public void navigationStateChanged(int flags) {
+        if ((flags & InvalidateTypes.URL) != 0
+                && mAwContents.hasAccessedInitialDocument()
+                && mAwContents.getDidAttemptLoad()) {

[Charlie Reis, 2015/03/02 23:09:31]

I don't think we need this, do we?  It seems like
NavigationController::GetPendingEntry() would tell you whether there's an
in-progress load or not.  (DidStartProvisionalLoad creates a pending entry.)

Is there a reason you need the "has there ever been a load" state, or is
GetPendingEntry() sufficient?  We won't have a visible URL to spoof if there
isn't a pending entry.  (GetVisibleEntry will just return the last committed
entry in that case.)

[mnaganov (inactive), 2015/03/03 08:55:48]

Indeed, my initial plan was to just use GetPendingEntry. Then I discovered that
WebContentsImpl::DidAccessInitialDocument discards the pending entry prior to
issuing  NavigationStateChanged notification, so when you check it here, it will
be null.

Then I tried to use the fact that NavigatorImpl::DidStartProvisionalLoad also
issues NavigationStateChanged notification immediately after creating the
pending entry, so I though I can catch it here, make a note to self via a
private flag, and then use this flag when I'll receive NavigationStateChanged
the second time due to a DOM mutation. But unfortunately, this approach was not
reliable due to asynchronous nature of notifications -- between the moment when
the pending entry has been set and the moment when this code receives
NavigationStateChanged, the pending entry could already had been discarded due
to a DOM mutation.

So I resorted to catching DidStartProvisionalLoadForFrame, which seems to work
reliably, as it's a synchronous callback.

+            // Hint the client to show the last committed url, as it may be unsafe to show
+            // the pending entry.
+            String url = mAwContents.getLastCommittedUrl();
+            url = TextUtils.isEmpty(url) ? "about:blank" : url;
+            mContentsClient.onPageStarted(url);
+            mContentsClient.onLoadResource(url);
+            mContentsClient.onProgressChanged(100);
+            mContentsClient.onPageFinished(url);
+        }
+    }
+
+    @Override
     public void toggleFullscreenModeForTab(boolean enterFullscreen) {
         if (enterFullscreen) {
             mContentViewClient.enterFullscreen();
         } else {
             mContentViewClient.exitFullscreen();
         }
     }
 
     private static class GetDisplayNameTask extends AsyncTask<Void, Void, String[]> {
         final int mProcessId;
@@ skipping 30 matching lines @@
          * or an empty string otherwise.
          */
         private String resolveFileName(String filePath) {
             if (mContentResolver == null || filePath == null) return "";
             Uri uri = Uri.parse(filePath);
             return ContentUriUtils.getDisplayName(
                     uri, mContentResolver, MediaStore.MediaColumns.DISPLAY_NAME);
         }
     }
 }