Remove access to WebContents in RWHVA::SynchronousFrameMetadata()

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 78c0d2271379a3629f84f3621665b921121d1daf..182c85f0d5937ab6e5750729a4667d5e08f7e5b0 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -1191,10 +1191,10 @@ void RenderWidgetHostViewAndroid::SynchronousFrameMetadata(
   OnFrameMetadataUpdated(frame_metadata.Clone(), false);
 
   // DevTools ScreenCast support for Android WebView.
-  WebContents* web_contents = content_view_core_->GetWebContents();
-  if (DevToolsAgentHost::HasFor(web_contents)) {
+  RenderFrameHost* frame_host = RenderViewHost::From(host_)->GetMainFrame();

[dgozman, 2016/11/08 18:41:08]

What about making RFDTAH::SynchronousSwapCompositorFrame function static, and
moving all this code there? Then we avoid exposing more public functions and
just issue instrumentation signals.

[Jinsuk Kim, 2016/11/08 22:21:12]

If I get it right, I need to pass |content_view_core_| for RFDTAH to get
WebContents from it. This will work but I will have to come back and make
another change to remove content_view_core which will be going away. 

How about adding GetAgentHost(RenderFrameHost*) (or FindAgentHost public)? It
won't depend on GetOrCreateFor(RenderFrameHost *).

[dgozman, 2016/11/08 22:47:29]

I suggest to add
RenderFrameDevToolsAgentHost::SynchronousSwapCompositorFrame(RenderFrameHost*,
cc::CompositorFrameMetadata)
and call it retrieving RFH as you do here.

[Jinsuk Kim, 2016/11/08 23:27:47]

Now I got it. Thanks! Done.

I named the static method 'Signal'SynchronousSwapCompositorFrame, which in turn
calls SynchronousSwapCompositorFrame which does the actual job.

+  if (frame_host && RenderFrameDevToolsAgentHost::HasFor(frame_host)) {
     scoped_refptr<DevToolsAgentHost> dtah =
-        DevToolsAgentHost::GetOrCreateFor(web_contents);
+        DevToolsAgentHost::GetOrCreateFor(frame_host);
     // Unblock the compositor.
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,