Use a resource throttle to implement shouldOverrideUrlLoading.

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.android_webview.AwContents.VisualStateCallback;
 import org.chromium.base.ThreadUtils;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.browser.WebContentsObserver;
@@ skipping 25 matching lines @@
         if (client == null) return;
         String unreachableWebDataUrl = AwContentsStatics.getUnreachableWebDataUrl();
         boolean isErrorUrl =
                 unreachableWebDataUrl != null && unreachableWebDataUrl.equals(validatedUrl);
         if (isMainFrame && !isErrorUrl) {
             client.onPageFinished(validatedUrl);
         }
     }
 
     @Override
-    public void didFailLoad(boolean isProvisionalLoad,
-            boolean isMainFrame, int errorCode, String description, String failingUrl) {
+    public void didFailLoad(boolean isProvisionalLoad, boolean isMainFrame, int errorCode,
+            String description, String failingUrl, boolean wasIgnoredByHandler) {
         AwContentsClient client = mAwContentsClient.get();
         if (client == null) return;
         String unreachableWebDataUrl = AwContentsStatics.getUnreachableWebDataUrl();
         boolean isErrorUrl =
                 unreachableWebDataUrl != null && unreachableWebDataUrl.equals(failingUrl);
         if (isMainFrame && !isErrorUrl && errorCode == NetError.ERR_ABORTED) {
             // Need to call onPageFinished for backwards compatibility with the classic webview.
             // See also AwContents.IoThreadClientImpl.onReceivedError.
-            client.onPageFinished(failingUrl);
+            // If the navigation was ignored because of shouldOverrideUrlLoading we have already
+            // called onPageFinished in
+            // AwContents.InterceptNavigationDelegateImpl.shouldIgnoreNavigation instead.
+            if (!wasIgnoredByHandler) {

[mnaganov (inactive), 2015/06/04 19:09:27]

nit: Why not to put this condition check into the outer 'if' statement?

[gsennton, 2015/06/08 14:07:23]

Done.

+                client.onPageFinished(failingUrl);
+            }
         }
     }
 
     @Override
     public void didNavigateMainFrame(final String url, String baseUrl,
             boolean isNavigationToDifferentPage, boolean isFragmentNavigation, int statusCode) {
         // Only invoke the onPageCommitVisible callback when navigating to a different page,
         // but not when navigating to a different fragment within the same page.
         if (isNavigationToDifferentPage) {
             ThreadUtils.postOnUiThread(new Runnable() {
@@ skipping 24 matching lines @@
         }
     }
 
     @Override
     public void didNavigateAnyFrame(String url, String baseUrl, boolean isReload) {
         final AwContentsClient client = mAwContentsClient.get();
         if (client == null) return;
         client.doUpdateVisitedHistory(url, isReload);
     }
 }