Do not send a frame swap ack from the browser until the frame is drawn

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index ce23b6606b2b03fb7e22278db70c37be14916e30..b77140a14ba4e18fae899fb62dcfbeac92d8adf9 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -434,6 +434,9 @@ RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget)
   }
 
   render_widget_host_->SetView(this);
+  render_widget_host_->SetAboutToWaitForBackingStoreCallback(
+      base::Bind(&RenderWidgetHostViewMac::SendPendingSwapAck,
+                 weak_factory_.GetWeakPtr()));
 }
 
 RenderWidgetHostViewMac::~RenderWidgetHostViewMac() {
@@ -574,6 +577,9 @@ bool RenderWidgetHostViewMac::CreateCompositedIOSurfaceLayer() {
 
 void RenderWidgetHostViewMac::DestroyCompositedIOSurfaceAndLayer(
     DestroyContextBehavior destroy_context_behavior) {
+  // Any pending frames will not be displayed, so ack them now.
+  SendPendingSwapAck();
+
   ScopedCAActionDisabler disabler;
 
   compositing_iosurface_.reset();
@@ -748,6 +754,10 @@ void RenderWidgetHostViewMac::WasHidden() {
   if (render_widget_host_->is_hidden())
     return;
 
+  // Any pending frames will not be displayed until this is shown again. Ack
+  // them now.
+  SendPendingSwapAck();
+
   // If we have a renderer, then inform it that we are being hidden so it can
   // reduce its resource utilization.
   render_widget_host_->WasHidden();
@@ -1321,6 +1331,7 @@ void RenderWidgetHostViewMac::CompositorSwapBuffers(
         compositing_iosurface_->CopyToVideoFrame(
             gfx::Rect(size), frame,
             base::Bind(callback, present_time));
+        SendPendingSwapAck();
         return;
       }
     }
@@ -1475,6 +1486,7 @@ bool RenderWidgetHostViewMac::DrawIOSurfaceWithoutCoreAnimation() {
   }
 
   SendPendingLatencyInfoToHost();
+  SendPendingSwapAck();
   return true;
 }
 
@@ -1652,19 +1664,14 @@ void RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped(
       "RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped");
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  AddPendingSwapAck(params.route_id,
+                    gpu_host_id,
+                    compositing_iosurface_ ?
+                        compositing_iosurface_->GetRendererID() : 0);
   CompositorSwapBuffers(params.surface_handle,
                         params.size,
                         params.scale_factor,
                         params.latency_info);
-
-  AcceleratedSurfaceMsg_BufferPresented_Params ack_params;
-  ack_params.sync_point = 0;
-  ack_params.renderer_id = compositing_iosurface_ ?
-      compositing_iosurface_->GetRendererID() : 0;
-  RenderWidgetHostImpl::AcknowledgeBufferPresent(params.route_id,
-                                                 gpu_host_id,
-                                                 ack_params);
-  render_widget_host_->AcknowledgeSwapBuffersToRenderer();
 }
 
 void RenderWidgetHostViewMac::AcceleratedSurfacePostSubBuffer(
@@ -1674,19 +1681,14 @@ void RenderWidgetHostViewMac::AcceleratedSurfacePostSubBuffer(
       "RenderWidgetHostViewMac::AcceleratedSurfacePostSubBuffer");
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  AddPendingSwapAck(params.route_id,
+                    gpu_host_id,
+                    compositing_iosurface_ ?
+                        compositing_iosurface_->GetRendererID() : 0);
   CompositorSwapBuffers(params.surface_handle,
                         params.surface_size,
                         params.surface_scale_factor,
                         params.latency_info);
-
-  AcceleratedSurfaceMsg_BufferPresented_Params ack_params;
-  ack_params.sync_point = 0;
-  ack_params.renderer_id = compositing_iosurface_ ?
-      compositing_iosurface_->GetRendererID() : 0;
-  RenderWidgetHostImpl::AcknowledgeBufferPresent(params.route_id,
-                                                 gpu_host_id,
-                                                 ack_params);
-  render_widget_host_->AcknowledgeSwapBuffersToRenderer();
 }
 
 void RenderWidgetHostViewMac::AcceleratedSurfaceSuspend() {
@@ -2060,6 +2062,29 @@ void RenderWidgetHostViewMac::TickPendingLatencyInfoDelay() {
   [compositing_iosurface_layer_ setNeedsDisplay];
 }
 
+void RenderWidgetHostViewMac::AddPendingSwapAck(
+    int32 route_id, int gpu_host_id, int32 renderer_id) {
+  DCHECK(!pending_swap_ack_);
+  pending_swap_ack_.reset(new PendingSwapAck(
+      route_id, gpu_host_id, renderer_id));
+}
+
+void RenderWidgetHostViewMac::SendPendingSwapAck() {
+  if (!pending_swap_ack_)
+    return;
+
+  AcceleratedSurfaceMsg_BufferPresented_Params ack_params;
+  ack_params.sync_point = 0;
+  ack_params.renderer_id = pending_swap_ack_->renderer_id;
+  RenderWidgetHostImpl::AcknowledgeBufferPresent(pending_swap_ack_->route_id,
+                                                 pending_swap_ack_->gpu_host_id,
+                                                 ack_params);
+  if (render_widget_host_)
+    render_widget_host_->AcknowledgeSwapBuffersToRenderer();
+
+  pending_swap_ack_.reset();
+}
+
 }  // namespace content
 
 // RenderWidgetHostViewCocoa ---------------------------------------------------