Limit outstanding surface draw swaps to max_frames_pending.

Avoid queueing up too many swaps on the GPU.

BUG=

Review URL: https://codereview.chromium.org/578383004

Cr-Commit-Position: refs/heads/master@{#296111}

cc/surfaces/display.cc

@@ -132,6 +132,14 @@ bool Display::Draw() {
   return true;
 }
 
+void Display::DidSwapBuffers() {
+  client_->DidSwapBuffers();
+}
+
+void Display::DidSwapBuffersComplete() {
+  client_->DidSwapBuffersComplete();
+}
+
 void Display::OnSurfaceDamaged(SurfaceId surface) {
   if (aggregator_ && aggregator_->previous_contained_surfaces().count(surface))
     client_->DisplayDamaged();
@@ -141,4 +149,10 @@ SurfaceId Display::CurrentSurfaceId() {
   return current_surface_id_;
 }
 
+int Display::GetMaxFramesPending() {
+  if (!output_surface_)
+    return OutputSurface::DEFAULT_MAX_FRAMES_PENDING;
+  return output_surface_->capabilities().max_frames_pending;
+}
+
 }  // namespace cc

cc/surfaces/display.h

@@ -47,6 +47,7 @@ class CC_SURFACES_EXPORT Display : public OutputSurfaceClient,
   bool Draw();
 
   SurfaceId CurrentSurfaceId();
+  int GetMaxFramesPending();
 
   // OutputSurfaceClient implementation.
   virtual void DeferredInitialize() OVERRIDE {}
@@ -55,8 +56,8 @@ class CC_SURFACES_EXPORT Display : public OutputSurfaceClient,
                                      base::TimeDelta interval) OVERRIDE {}
   virtual void SetNeedsRedrawRect(const gfx::Rect& damage_rect) OVERRIDE {}
   virtual void BeginFrame(const BeginFrameArgs& args) OVERRIDE {}
-  virtual void DidSwapBuffers() OVERRIDE {}
-  virtual void DidSwapBuffersComplete() OVERRIDE {}
+  virtual void DidSwapBuffers() OVERRIDE;
+  virtual void DidSwapBuffersComplete() OVERRIDE;
   virtual void ReclaimResources(const CompositorFrameAck* ack) OVERRIDE {}
   virtual void DidLoseOutputSurface() OVERRIDE {}
   virtual void SetExternalDrawConstraints(

cc/surfaces/display_client.h

@@ -15,6 +15,8 @@ class DisplayClient {
  public:
   virtual scoped_ptr<OutputSurface> CreateOutputSurface() = 0;
   virtual void DisplayDamaged() = 0;
+  virtual void DidSwapBuffers() = 0;
+  virtual void DidSwapBuffersComplete() = 0;
 
  protected:
   virtual ~DisplayClient() {}

content/browser/compositor/onscreen_display_client.cc

@@ -21,6 +21,8 @@ OnscreenDisplayClient::OnscreenDisplayClient(
           new cc::Display(this, manager, HostSharedBitmapManager::current())),
       task_runner_(task_runner),
       scheduled_draw_(false),
+      deferred_draw_(false),
+      pending_frames_(0),
       weak_ptr_factory_(this) {
 }
 
@@ -33,9 +35,19 @@ scoped_ptr<cc::OutputSurface> OnscreenDisplayClient::CreateOutputSurface() {
 }
 
 void OnscreenDisplayClient::DisplayDamaged() {
-  if (scheduled_draw_)
+  if (scheduled_draw_ || deferred_draw_)
     return;
   TRACE_EVENT0("content", "OnscreenDisplayClient::DisplayDamaged");
+  if (pending_frames_ >= display_->GetMaxFramesPending()) {
+    deferred_draw_ = true;
+  } else {
+    ScheduleDraw();
+  }
+}
+
+void OnscreenDisplayClient::ScheduleDraw() {
+  DCHECK(!deferred_draw_);
+  DCHECK(!scheduled_draw_);
   scheduled_draw_ = true;
   task_runner_->PostTask(
       FROM_HERE,
@@ -48,4 +60,16 @@ void OnscreenDisplayClient::Draw() {
   display_->Draw();
 }
 
+void OnscreenDisplayClient::DidSwapBuffers() {
+  pending_frames_++;
+}
+
+void OnscreenDisplayClient::DidSwapBuffersComplete() {
+  pending_frames_--;
+  if ((pending_frames_ < display_->GetMaxFramesPending()) && deferred_draw_) {
+    deferred_draw_ = false;
+    ScheduleDraw();
+  }
+}
+
 }  // namespace content

content/browser/compositor/onscreen_display_client.h

@@ -34,14 +34,21 @@ class OnscreenDisplayClient : cc::DisplayClient {
   // cc::DisplayClient implementation.
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface() OVERRIDE;
   virtual void DisplayDamaged() OVERRIDE;
+  virtual void DidSwapBuffers() OVERRIDE;
+  virtual void DidSwapBuffersComplete() OVERRIDE;
 
  private:
+  void ScheduleDraw();
   void Draw();
 
   scoped_ptr<cc::OutputSurface> output_surface_;
   scoped_ptr<cc::Display> display_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   bool scheduled_draw_;
+  // True if a draw should be scheduled, but it's hit the limit on max frames
+  // pending.
+  bool deferred_draw_;
+  int pending_frames_;
 
   base::WeakPtrFactory<OnscreenDisplayClient> weak_ptr_factory_;
 

mojo/services/surfaces/surfaces_impl.cc

@@ -98,4 +98,10 @@ scoped_ptr<cc::OutputSurface> SurfacesImpl::CreateOutputSurface() {
 void SurfacesImpl::DisplayDamaged() {
 }
 
+void SurfacesImpl::DidSwapBuffers() {
+}
+
+void SurfacesImpl::DidSwapBuffersComplete() {
+}
+
 }  // namespace mojo

mojo/services/surfaces/surfaces_impl.h

@@ -52,6 +52,8 @@ class SurfacesImpl : public InterfaceImpl<Surface>,
   // DisplayClient implementation.
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface() OVERRIDE;
   virtual void DisplayDamaged() OVERRIDE;
+  virtual void DidSwapBuffers() OVERRIDE;
+  virtual void DidSwapBuffersComplete() OVERRIDE;
 
   cc::SurfaceFactory* factory() { return &factory_; }