Revert 251918 "Do not send a frame swap ack from the browser unt..."

trunk/src/content/browser/renderer_host/render_widget_host_view_mac.h

Index: trunk/src/content/browser/renderer_host/render_widget_host_view_mac.h
===================================================================
--- trunk/src/content/browser/renderer_host/render_widget_host_view_mac.h	(revision 252030)
+++ trunk/src/content/browser/renderer_host/render_widget_host_view_mac.h	(working copy)
@@ -398,11 +398,8 @@
   // someone (other than superview) has retained |cocoa_view_|.
   RenderWidgetHostImpl* render_widget_host_;
 
-  // 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.
+  // This is true when we are currently painting and thus should handle extra
+  // paint requests by expanding the invalid rect rather than actually painting.
   bool about_to_validate_and_paint_;
 
   // This is true when we have already scheduled a call to
@@ -494,24 +491,10 @@
   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.