android: Fix ContentViewCore and RenderWidgetHostViewAndroid lifetime issue

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 4cb6da8994f4dd65a52654b0104c558c83adf513..9442fcd38bece895a2f4a4dc6d6501fdb9677c50 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -1679,6 +1679,15 @@ void ContentViewCoreImpl::OnSmartClipDataExtracted(
       env, obj.obj(), jresult.obj());
 }
 
+void ContentViewCoreImpl::OnDetachedFromWebContents(WebContents* web_contents) {

[Ted C, 2014/01/23 01:28:42]

Looking more at this, why don't you do this in ContentViewCoreImpl's destructor?

ContentViewCoreImpl is owned by the WebContents and will deleted when it is.  If
you look at ContentViewCoreImpl::ContentViewUserData, that sets up the
relationship and should be ensuring this is deleted before the web contents.

Maybe that would simplify this a bit?

[powei, 2014/01/23 01:38:02]

My first instinct was to put it in the destructor as well, but that did not
work.

I think the order is that the destructor of WebContentsImpl is called, then
ContentViewUserData goes out of scope and CVC gets deleted.  

[Ted C, 2014/01/23 02:00:15]

Hmm...that is unfortunate.  If that is the case, I'd rather make this class (or
even WebContentsViewAndroid) a WebContentsObserver instead of piggy backing on
the java bridge class.  There is actually no requirement that this class have a
WebContentsObserverAndroid attached to it (granted they always do), but I think
it would be cleaner for one of these two classes to maintain the state
internally instead of relying on a hidden property.

[powei, 2014/01/23 02:38:40]

Done.  Turns out ContentViewCoreImpl is already a WebContentsObserver.  Color me
embarrassed.

+  DCHECK_EQ(GetWebContents(), web_contents);
+
+  WebContentsViewAndroid* wcva =
+    static_cast<WebContentsViewAndroid*>(GetWebContents()->GetView());

[Ted C, 2014/01/23 01:28:42]

+2

[powei, 2014/01/23 01:38:02]

Done.

+  DCHECK(wcva);
+  wcva->SetContentViewCore(NULL);
+}
+
 // This is called for each ContentView.
 jlong Init(JNIEnv* env, jobject obj,
            jboolean hardware_accelerated,