[PPAPI] ResourceVar now reference counts its PP_Resource in the plugin.

ppapi/shared_impl/resource_var.h

 // Copyright 2013 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 PPAPI_SHARED_IMPL_RESOURCE_VAR_H_
 #define PPAPI_SHARED_IMPL_RESOURCE_VAR_H_
 
-#include "ipc/ipc_message.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 #include "ppapi/shared_impl/var.h"
 
+namespace IPC {
+class Message;
+}
+
 namespace ppapi {
 
 // Represents a resource Var.
 class PPAPI_SHARED_EXPORT ResourceVar : public Var {
  public:
-  // Makes a null resource var.
-  ResourceVar();
+  // Gets the resource ID associated with this var.
+  // This is 0 if a resource is still pending (only possible on the host side).
+  // NOTE: This can return a PP_Resource with a reference count of 0 on the
+  // plugin side. It should be AddRef'd if the resource is passed to the user.
+  virtual PP_Resource GetPPResource() const = 0;
 
-  // Makes a resource var with an existing plugin-side resource.
-  explicit ResourceVar(PP_Resource pp_resource);
-
-  // Makes a resource var with a pending resource host.
-  // The |creation_message| contains instructions on how to create the
-  // plugin-side resource. Its type depends on the type of resource.
-  explicit ResourceVar(const IPC::Message& creation_message);
-
-  virtual ~ResourceVar();
-
-  // Gets the resource ID associated with this var.
-  // This is 0 if a resource is still pending.
-  PP_Resource pp_resource() const { return pp_resource_; }
-
-  // Gets the message for creating a plugin-side resource.
-  // May be an empty message.
-  const IPC::Message& creation_message() const { return creation_message_; }
+  // Gets the message for creating a plugin-side resource. Returns NULL if the
+  // message is empty (which is always true on the plugin side).
+  virtual const IPC::Message* GetCreationMessage() const;
 
   // Determines whether this is a pending resource.
-  // This is true if the pp_resource is 0 and there is a non-empty
-  // creation_message.
-  bool IsPending() const;
+  // This is true if, on the host side, the there is a creation_message and no
+  // PP_Resource.
+  virtual bool IsPending() const = 0;
 
   // Var override.
   virtual ResourceVar* AsResourceVar() OVERRIDE;
   virtual PP_VarType GetType() const OVERRIDE;
 
   // Helper function that converts a PP_Var to a ResourceVar. This will
   // return NULL if the PP_Var is not of Resource type.
   static ResourceVar* FromPPVar(PP_Var var);
 
+ protected:
+  ResourceVar();
+
+  virtual ~ResourceVar();
+
  private:
-  // Real resource ID in the plugin. 0 if one has not yet been created
-  // (indicating that there is a pending host resource).
-  PP_Resource pp_resource_;
-
-  // If the plugin-side resource has not yet been created, carries a message to
-  // create a resource of the specific type on the plugin side.
-  // Otherwise, carries an empty message.
-  IPC::Message creation_message_;
-
   DISALLOW_COPY_AND_ASSIGN(ResourceVar);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_RESOURCE_VAR_H_