Allocate a FrameSinkId for RenderWidgetHostViewAura in mus+ash

RenderWidgetHostViewChildFrame expects its parent to have a valid
FrameSinkId. Make sure RenderWidgetHostViewAura has a FrameSinkId even
if DelegatedFrameHost is not used (in mus+ash).

BUG=706553
TBR=jam@chromium.org

Review-Url: https://codereview.chromium.org/2847253003
Cr-Commit-Position: refs/heads/master@{#468179}

content/browser/renderer_host/render_widget_host_view_aura.cc

@@ -396,6 +396,7 @@ RenderWidgetHostViewAura::RenderWidgetHostViewAura(RenderWidgetHost* host,
       is_guest_view_hack_(is_guest_view_hack),
       device_scale_factor_(0.0f),
       event_handler_(new RenderWidgetHostViewEventHandler(host_, this, this)),
+      frame_sink_id_(host_->AllocateFrameSinkId(is_guest_view_hack_)),
       weak_ptr_factory_(this) {
   if (!is_guest_view_hack_)
     host_->SetView(this);
@@ -1932,16 +1933,13 @@ void RenderWidgetHostViewAura::CreateDelegatedFrameHostClient() {
   if (IsMus())
     return;
 
-  cc::FrameSinkId frame_sink_id =
-      host_->AllocateFrameSinkId(is_guest_view_hack_);
-
   // Tests may set |delegated_frame_host_client_|.
   if (!delegated_frame_host_client_) {
     delegated_frame_host_client_ =
         base::MakeUnique<DelegatedFrameHostClientAura>(this);
   }
   delegated_frame_host_ = base::MakeUnique<DelegatedFrameHost>(
-      frame_sink_id, delegated_frame_host_client_.get());
+      frame_sink_id_, delegated_frame_host_client_.get());
   if (renderer_compositor_frame_sink_) {
     delegated_frame_host_->DidCreateNewRendererCompositorFrameSink(
         renderer_compositor_frame_sink_);
@@ -2282,8 +2280,7 @@ void RenderWidgetHostViewAura::OnDidNavigateMainFrameToNewPage() {
 }
 
 cc::FrameSinkId RenderWidgetHostViewAura::GetFrameSinkId() {
-  return delegated_frame_host_ ? delegated_frame_host_->GetFrameSinkId()
-                               : cc::FrameSinkId();
+  return frame_sink_id_;
 }
 
 cc::SurfaceId RenderWidgetHostViewAura::SurfaceIdForTesting() const {

content/browser/renderer_host/render_widget_host_view_aura.h

@@ -590,6 +590,8 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // provides an implementation, and directs events to |host_|.
   std::unique_ptr<RenderWidgetHostViewEventHandler> event_handler_;
 
+  cc::FrameSinkId frame_sink_id_;
+
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);