Delete background tab IOSurfaces on Mac.

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 09e861d16d3eef2c3b10507ccd62f820d9d3fb59..c36ff4b0b83c1eaf9079610ea35dc96977a5216f 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -24,6 +24,7 @@ class CommandLine;
 class GpuMessageFilter;
 class RendererMainThread;
 class RenderWidgetHelper;
+struct ViewHostMsg_UpdateRect_Params;
 
 namespace base {
 class WaitableEvent;
@@ -162,6 +163,12 @@ class CONTENT_EXPORT RenderProcessHostImpl
   void OnRevealFolderInOS(const FilePath& path);
   void OnSavedPageAsMHTML(int job_id, int64 mhtml_file_size);
 
+  // CompositorSurfaceBuffersSwapped handler when there's no RWH.
+  void OnCompositorSurfaceBuffersSwappedNoHost(int32 surface_id,
+                                               uint64 surface_handle,
+                                               int32 route_id,
+                                               int32 gpu_process_host_id);
+
   // Generates a command line to be used to spawn a renderer and appends the
   // results to |*command_line|.
   void AppendRendererCommandLine(CommandLine* command_line) const;