[Android WebView] Implement a better OnReceivedError callback

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 a248d3988c34e9ec14d88fc49546ba0ab8e4d166..4746aa95eafc535c097c069b532c065f9070039d 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
@@ -8,7 +8,6 @@ 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;
-import org.chromium.net.NetError;
 
 import java.lang.ref.WeakReference;
 
@@ -51,29 +50,13 @@ public class AwWebContentsObserver extends WebContentsObserver {
         String unreachableWebDataUrl = AwContentsStatics.getUnreachableWebDataUrl();
         boolean isErrorUrl =
                 unreachableWebDataUrl != null && unreachableWebDataUrl.equals(failingUrl);
-        if (isErrorUrl) return;
-        if (errorCode != NetError.ERR_ABORTED) {
-            // This error code is generated for the following reasons:
-            // - WebView.stopLoading is called,
-            // - the navigation is intercepted by the embedder via shouldOverrideNavigation.
-            //
-            // The Android WebView does not notify the embedder of these situations using
-            // this error code with the WebViewClient.onReceivedError callback.
-            AwContentsClient.AwWebResourceRequest request =
-                    new AwContentsClient.AwWebResourceRequest();
-            request.url = failingUrl;
-            request.isMainFrame = isMainFrame;
-            // TODO(mnaganov): Fill in the rest of AwWebResourceRequest fields. Probably,
-            // we will have to actually invoke the error callback from the network delegate
-            // in order to catch load errors for all resources.
-            AwContentsClient.AwWebResourceError error = new AwContentsClient.AwWebResourceError();
-            error.errorCode = ErrorCodeConversionHelper.convertErrorCode(errorCode);
-            error.description = description;
-            mAwContentsClient.onReceivedError(request, error);
-        }
-        if (isMainFrame) {
+        if (isMainFrame && !isErrorUrl) {
             // Need to call onPageFinished after onReceivedError (if there is an error) for
             // backwards compatibility with the classic webview.
+            //
+            // onReceivedError is called from AwContents.IoThreadClientImpl.onReceivedError
+            // It is not possible to move this code there, because onReceivedError is not called
+            // when WebView receives 204 (No content) reply from the server.

[sgurun-gerrit only, 2015/03/17 00:30:04]

huh, this sentence made me confused because of use or present tense I think. is
onReceivedError supposed to be called when server sends a 204?
consider writing a test case for this condition (i.e. a client still receiving
onpagefinished when server returns a 204). 

[mnaganov (inactive), 2015/03/17 15:29:09]

I rethought this and change an approach a bit. To make sure that we don't have a
race between posting onReceivedError from AwContents.IoThreadClientImpl and
onPageFinished from here (I encountered some flakiness in tests because of
that), I made IoThreadClientImpl to post both events, except for the case when
the error code is ERR_ABORTED. But as in this case only onPageFinished must be
emitted, and since we only emit it for the main frame, we will catch all the
possible situations here, in WebContentsObserver.didFailLoad.

I actually discovered this fact through a test that opens a popup window which
opens a url that returns 204. But I also added a test that checks this for the
main resource.

             mAwContentsClient.onPageFinished(failingUrl);
         }
     }