Add acknowledgement messages for PluginMsg_UpdateGeometry

chrome/renderer/webplugin_delegate_proxy.h

Index: chrome/renderer/webplugin_delegate_proxy.h
===================================================================
--- chrome/renderer/webplugin_delegate_proxy.h	(revision 33240)
+++ chrome/renderer/webplugin_delegate_proxy.h	(working copy)
@@ -22,6 +22,11 @@
 #include "webkit/glue/webplugininfo.h"
 #include "webkit/glue/webplugin_delegate.h"
 
+#if defined(OS_MACOSX)
+#include "base/hash_tables.h"
+#include "base/linked_ptr.h"
+#endif
+
 struct NPObject;
 class NPObjectStub;
 struct NPVariant_Param;
@@ -133,6 +138,10 @@
                                   intptr_t notify_data);
   void OnDeferResourceLoading(int resource_id, bool defer);
 
+#if defined(OS_MACOSX)
+  void OnUpdateGeometry_ACK(int ack_key);
+#endif
+
   // Draw a graphic indicating a crashed plugin.
   void PaintSadPlugin(WebKit::WebCanvas* canvas, const gfx::Rect& rect);
 
@@ -156,6 +165,24 @@
   // point the window has already been destroyed).
   void WillDestroyWindow();
 
+#if defined(OS_MACOSX)
+  // The Mac TransportDIB implementation uses base::SharedMemory, which
+  // cannot be disposed of if an in-flight UpdateGeometry message refers to
+  // the shared memory file descriptor.  The old_transport_dibs_ map holds
+  // old TransportDIBs waiting to die.  It's keyed by the |ack_key| values
+  // used in UpdateGeometry messages.  When an UpdateGeometry_ACK message
+  // arrives, the associated RelatedTransportDIBs can be released.
+  struct RelatedTransportDIBs {
+    linked_ptr<TransportDIB> backing_store;
+    linked_ptr<TransportDIB> transport_store;
+    linked_ptr<TransportDIB> background_store;
+  };
+
+  typedef base::hash_map<int, RelatedTransportDIBs> OldTransportDIBMap;
+
+  OldTransportDIBMap old_transport_dibs_;
+#endif  // OS_MACOSX
+
   base::WeakPtr<RenderView> render_view_;
   webkit_glue::WebPlugin* plugin_;
   bool windowless_;