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

content/browser/renderer_host/render_widget_host_view_mac.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 #include <list>
 #include <map>
@@ skipping 380 matching lines @@
   gfx::Range ConvertCharacterRangeToCompositionRange(
       const gfx::Range& request_range);
 
   // These member variables should be private, but the associated ObjC class
   // needs access to them and can't be made a friend.
 
   // The associated Model.  Can be NULL if Destroy() is called when
   // someone (other than superview) has retained |cocoa_view_|.
   RenderWidgetHostImpl* render_widget_host_;
 
-  // This is true when we are currently painting and thus should handle extra
-  // paint requests by expanding the invalid rect rather than actually painting.
+  // This is true when we are currently painting. In the legacy renderer, this
+  // means we should handle extra paint requests by expanding the invalid rect
+  // rather than actually painting. In hardware compositing it means that we
+  // are inside a draw callback and should not wait for frames to draw before
+  // acknowledging them.
   bool about_to_validate_and_paint_;
 
   // This is true when we have already scheduled a call to
   // |-callSetNeedsDisplayInRect:| but it has not been fulfilled yet.  Used to
   // prevent us from scheduling multiple calls.
   bool call_set_needs_display_in_rect_pending_;
 
   // Whether last rendered frame was accelerated.
   bool last_frame_was_accelerated_;
 
@@ skipping 63 matching lines @@
 
   int window_number() const;
 
   float scale_factor() const;
 
   void AddPendingLatencyInfo(
       const std::vector<ui::LatencyInfo>& latency_info);
   void SendPendingLatencyInfoToHost();
   void TickPendingLatencyInfoDelay();
 
+  void SendPendingSwapAck();
+
  private:
   friend class RenderWidgetHostView;
   friend class RenderWidgetHostViewMacTest;
 
+  struct PendingSwapAck {
+    PendingSwapAck(int32 route_id, int gpu_host_id, int32 renderer_id)
+        : route_id(route_id),
+          gpu_host_id(gpu_host_id),
+          renderer_id(renderer_id) {}
+    int32 route_id;
+    int gpu_host_id;
+    int32 renderer_id;
+  };
+  scoped_ptr<PendingSwapAck> pending_swap_ack_;
+  void AddPendingSwapAck(int32 route_id, int gpu_host_id, int32 renderer_id);
+
   // The view will associate itself with the given widget. The native view must
   // be hooked up immediately to the view hierarchy, or else when it is
   // deleted it will delete this out from under the caller.
   explicit RenderWidgetHostViewMac(RenderWidgetHost* widget);
 
   // Returns whether this render view is a popup (autocomplete window).
   bool IsPopup() const;
 
   // Shuts down the render_widget_host_.  This is a separate function so we can
   // invoke it from the message loop.
@@ skipping 86 matching lines @@
   scoped_ptr<RenderWidgetHostViewFrameSubscriber> frame_subscriber_;
 
   base::WeakPtrFactory<RenderWidgetHostViewMac>
       software_frame_weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMac);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_