Cache image data objects.

ppapi/proxy/ppb_image_data_proxy.h

Index: ppapi/proxy/ppb_image_data_proxy.h
diff --git a/ppapi/proxy/ppb_image_data_proxy.h b/ppapi/proxy/ppb_image_data_proxy.h
index ee80cc05f9bc477409632e8b24f4e439e3855f4c..812fd783937cb91d79c03adb4b2beca67ebfb795 100644
--- a/ppapi/proxy/ppb_image_data_proxy.h
+++ b/ppapi/proxy/ppb_image_data_proxy.h
@@ -50,6 +50,7 @@ class ImageData : public ppapi::Resource,
 
   // Resource overrides.
   virtual ppapi::thunk::PPB_ImageData_API* AsPPB_ImageData_API() OVERRIDE;
+  virtual void LastPluginRefWasDeleted() OVERRIDE;
 
   // PPB_ImageData API.
   virtual PP_Bool Describe(PP_ImageDataDesc* desc) OVERRIDE;
@@ -61,6 +62,9 @@ class ImageData : public ppapi::Resource,
 
   const PP_ImageDataDesc& desc() const { return desc_; }
 
+  // Fills the contents of the image with 0.
+  void ZeroContents();
+
 #if !defined(OS_NACL)
   static ImageHandle NullHandle();
   static ImageHandle HandleFromInt(int32_t i);
@@ -99,7 +103,7 @@ class PPB_ImageData_Proxy : public InterfaceProxy {
   static const ApiID kApiID = API_ID_PPB_IMAGE_DATA;
 
  private:
-  // Message handlers.
+  // Plugin->Host message handlers.
   void OnHostMsgCreate(PP_Instance instance,
                        int32_t format,
                        const PP_Size& size,
@@ -115,6 +119,9 @@ class PPB_ImageData_Proxy : public InterfaceProxy {
                            std::string* image_data_desc,
                            base::SharedMemoryHandle* result_image_handle);
 
+  // Host->Plugin message handlers.
+  void OnPluginMsgNotifyUnusedImageData(const HostResource& old_image_data);
+
   DISALLOW_COPY_AND_ASSIGN(PPB_ImageData_Proxy);
 };