DirectCompositorFrameSink Uses CompositorFrameSinkSupport

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 2012 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.
 
 #include "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include <utility>
 
@@ skipping 1471 matching lines @@
   if (host_)
     host_->Send(new ViewMsg_SetBeginFramePaused(host_->GetRoutingID(), false));
   view_.GetWindowAndroid()->AddObserver(this);
   // When using browser compositor, DelegatedFrameHostAndroid provides the BFS.
   if (!using_browser_compositor_)
     SetBeginFrameSource(view_.GetWindowAndroid()->GetBeginFrameSource());
 
   ui::WindowAndroidCompositor* compositor =
       view_.GetWindowAndroid()->GetCompositor();
   if (compositor) {
-    delegated_frame_host_->RegisterFrameSinkHierarchy(
-        compositor->GetFrameSinkId());
+    static_cast<CompositorImpl*>(compositor)

[boliu, 2017/01/27 23:17:59]

nit: cast in the assignment line

also, what's the argument for this going through the browser compositor? (not
that it's wrong or anything)

[Alex Z., 2017/01/29 14:58:51]

Done.

In the case for desktop chrome, there's a mojo message pipe between the browser
process and gpu process. Mojo would automatically queue messages like 
AddChileFrameSink() until a CompositorFrameSink is attached.

We decided to manage manually the queue here so that it'll be easier to unify
all CompositorFrameSinks later on.

[boliu, 2017/01/30 17:20:22]

That doesn't actually answer my question

Is the answer that desktop also goes through browser compositor as well, and
this is just matching desktop?

[boliu, 2017/01/30 21:13:51]

this is still unanswered?

[Fady Samuel, 2017/01/30 21:45:52]

We cannot currently register a BeginFrame hierarchy until the parent has created
a CompositorFrameSink. The parent knows when it has created a
CompositorFrameSink so setting up registration there seems to make sense.

This simplifies display compositor restart, because we can easily call
AddChildFrameSinks whenever until the parent creates a CompositorFrameSink.

+        ->AddChildFrameSink(delegated_frame_host_->GetFrameSinkId());
   }
 }
 
 void RenderWidgetHostViewAndroid::StopObservingRootWindow() {
   if (!(view_.GetWindowAndroid())) {
     DCHECK(!observing_root_window_);
     return;
   }
 
   if (!observing_root_window_)
@@ skipping 563 matching lines @@
   ui::WindowAndroidCompositor* compositor = window_android->GetCompositor();
   if (!compositor)
     return;
 
   overscroll_controller_ = base::MakeUnique<OverscrollControllerAndroid>(
       overscroll_refresh_handler, compositor,
       ui::GetScaleFactorForNativeView(GetNativeView()));
 }
 
 }  // namespace content