Hoist SetNeedsBeginFrame messages up to the RWHostImpl

content/browser/frame_host/render_widget_host_view_child_frame.cc

Index: content/browser/frame_host/render_widget_host_view_child_frame.cc
diff --git a/content/browser/frame_host/render_widget_host_view_child_frame.cc b/content/browser/frame_host/render_widget_host_view_child_frame.cc
index 736d16e9f871598e24d8f59f4c065203dbe9ba68..0b7094aa8bd77e3ec7f9c98dc6d0f96c910b0385 100644
--- a/content/browser/frame_host/render_widget_host_view_child_frame.cc
+++ b/content/browser/frame_host/render_widget_host_view_child_frame.cc
@@ -48,7 +48,6 @@ RenderWidgetHostViewChildFrame::RenderWidgetHostViewChildFrame(
       ack_pending_count_(0),
       frame_connector_(nullptr),
       begin_frame_source_(nullptr),
-      observing_begin_frame_source_(false),
       parent_surface_client_id_(0),
       weak_factory_(this) {
   id_allocator_.reset(new cc::SurfaceIdAllocator(AllocateSurfaceClientId()));
@@ -110,16 +109,6 @@ void RenderWidgetHostViewChildFrame::InitAsChild(
   NOTREACHED();
 }
 
-bool RenderWidgetHostViewChildFrame::OnMessageReceived(
-    const IPC::Message& message) {
-  bool handled = true;
-  IPC_BEGIN_MESSAGE_MAP(RenderWidgetHostViewChildFrame, message)
-    IPC_MESSAGE_HANDLER(ViewHostMsg_SetNeedsBeginFrames, OnSetNeedsBeginFrames)
-    IPC_MESSAGE_UNHANDLED(handled = false)
-  IPC_END_MESSAGE_MAP()
-  return handled;
-}
-
 RenderWidgetHost* RenderWidgetHostViewChildFrame::GetRenderWidgetHost() const {
   return host_;
 }
@@ -642,10 +631,11 @@ void RenderWidgetHostViewChildFrame::ReturnResources(
 
 void RenderWidgetHostViewChildFrame::SetBeginFrameSource(
     cc::BeginFrameSource* source) {
-  if (begin_frame_source_ && observing_begin_frame_source_)
+  bool needs_begin_frames = host_->needs_begin_frames();
+  if (begin_frame_source_ && needs_begin_frames)
     begin_frame_source_->RemoveObserver(this);
   begin_frame_source_ = source;
-  if (begin_frame_source_ && observing_begin_frame_source_)
+  if (begin_frame_source_ && needs_begin_frames)
     begin_frame_source_->AddObserver(this);
 }
 
@@ -665,18 +655,15 @@ void RenderWidgetHostViewChildFrame::OnBeginFrameSourcePausedChanged(
   // Only used on Android WebView.
 }
 
-void RenderWidgetHostViewChildFrame::OnSetNeedsBeginFrames(
+void RenderWidgetHostViewChildFrame::SetNeedsBeginFrames(
     bool needs_begin_frames) {

[no sievers, 2016/08/22 18:13:56]

I don't quite understand when this codepath is ever used - i.e. when this is not
a RWHVGuest which overrides this (through the generic OnMsgReceived forwarding
to the |platform_view_| before your patch, and the SetNeedsBF() override after),
other than in tests maybe.

But your patch doesn't look like it would change the behavior. Might be worth
following up though if we maybe route the SetNeeds...() vs. actual sending of BF
through different views - it's definitely confusing that the logic exists here
and then SetNeedsBF() (and *only* that is overriden in RWHVGuest).

-  if (observing_begin_frame_source_ == needs_begin_frames)
+  if (!begin_frame_source_)
     return;
 
-  observing_begin_frame_source_ = needs_begin_frames;
-  if (begin_frame_source_) {
-    if (observing_begin_frame_source_)
-      begin_frame_source_->AddObserver(this);
-    else
-      begin_frame_source_->RemoveObserver(this);
-  }
+  if (needs_begin_frames)
+    begin_frame_source_->AddObserver(this);
+  else
+    begin_frame_source_->RemoveObserver(this);
 }
 
 InputEventAckState RenderWidgetHostViewChildFrame::FilterInputEvent(