content: Cleanup GpuMemoryBufferImpl destruction.

content/common/gpu/client/gpu_memory_buffer_impl.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 CONTENT_COMMON_GPU_CLIENT_GPU_MEMORY_BUFFER_IMPL_H_
 #define CONTENT_COMMON_GPU_CLIENT_GPU_MEMORY_BUFFER_IMPL_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/gpu_memory_buffer.h"
 #include "ui/gfx/size.h"
 
 namespace content {
 
 // Provides common implementation of a GPU memory buffer.
 class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
  public:
   typedef base::Callback<void(scoped_ptr<GpuMemoryBufferImpl> buffer)>
       CreationCallback;
   typedef base::Callback<void(const gfx::GpuMemoryBufferHandle& handle)>
       AllocationCallback;
+  typedef base::Closure DestructionCallback;
 
   virtual ~GpuMemoryBufferImpl();
 
   // Creates a GPU memory buffer instance with |size| and |internalformat| for
   // |usage| by the current process and |client_id|.
   static void Create(const gfx::Size& size,
                      unsigned internalformat,
                      unsigned usage,
                      int client_id,
                      const CreationCallback& callback);
 
   // Allocates a GPU memory buffer with |size| and |internalformat| for |usage|
   // by |child_process| and |child_client_id|. The |handle| returned can be
   // used by the |child_process| to create an instance of this class.
   static void AllocateForChildProcess(const gfx::Size& size,
                                       unsigned internalformat,
                                       unsigned usage,
                                       base::ProcessHandle child_process,
                                       int child_client_id,
                                       const AllocationCallback& callback);
 
   // Notify that GPU memory buffer has been deleted by |child_process|.
   static void DeletedByChildProcess(gfx::GpuMemoryBufferType type,
                                     const gfx::GpuMemoryBufferId& id,
                                     base::ProcessHandle child_process);
 
   // Creates an instance from the given |handle|. |size| and |internalformat|
-  // should match what was used to allocate the |handle|.
+  // should match what was used to allocate the |handle|. |callback| is
+  // called when instance is deleted, which is not necessarily on the same
+  // thread as this function was called on and instance was created on.
   static scoped_ptr<GpuMemoryBufferImpl> CreateFromHandle(
       const gfx::GpuMemoryBufferHandle& handle,
       const gfx::Size& size,
-      unsigned internalformat);
+      unsigned internalformat,
+      const DestructionCallback& callback);
 
   // Returns true if |internalformat| is a format recognized by this base class.
   static bool IsFormatValid(unsigned internalformat);
 
   // Returns true if |usage| is recognized by this base class.
   static bool IsUsageValid(unsigned usage);
 
   // Returns the number of bytes per pixel that must be used by an
   // implementation when using |internalformat|.
   static size_t BytesPerPixel(unsigned internalformat);
 
   // Overridden from gfx::GpuMemoryBuffer:
   virtual bool IsMapped() const OVERRIDE;
 
  protected:
-  GpuMemoryBufferImpl(const gfx::Size& size, unsigned internalformat);
+  GpuMemoryBufferImpl(const gfx::Size& size,
+                      unsigned internalformat,
+                      const DestructionCallback& callback);
 
   const gfx::Size size_;
   const unsigned internalformat_;
+  const DestructionCallback callback_;
   bool mapped_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuMemoryBufferImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_GPU_MEMORY_BUFFER_IMPL_H_