[WIP] Add SharedMemoryTracker to dump base::SharedMemory usage

gpu/command_buffer/common/buffer.h

 // Copyright (c) 2014 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 GPU_COMMAND_BUFFER_COMMON_BUFFER_H_
 #define GPU_COMMAND_BUFFER_COMMON_BUFFER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/shared_memory.h"
 #include "base/trace_event/memory_allocator_dump.h"
 #include "gpu/gpu_export.h"
 
 namespace base {
   class SharedMemory;
 }
 
 namespace gpu {
 
 class GPU_EXPORT BufferBacking {
  public:
   virtual ~BufferBacking() {}
-  virtual bool is_shared() const;
+  virtual base::SharedMemory* shared_memory();
   virtual void* GetMemory() const = 0;
   virtual size_t GetSize() const = 0;
 };
 
 class GPU_EXPORT SharedMemoryBufferBacking : public BufferBacking {
  public:
   SharedMemoryBufferBacking(std::unique_ptr<base::SharedMemory> shared_memory,
                             size_t size);
   ~SharedMemoryBufferBacking() override;
-  bool is_shared() const override;
+  base::SharedMemory* shared_memory() override;
   void* GetMemory() const override;
   size_t GetSize() const override;
-  base::SharedMemory* shared_memory() { return shared_memory_.get(); }
 
  private:
   std::unique_ptr<base::SharedMemory> shared_memory_;
   size_t size_;
   DISALLOW_COPY_AND_ASSIGN(SharedMemoryBufferBacking);
 };
 
 // Buffer owns a piece of shared-memory of a certain size.
 class GPU_EXPORT Buffer : public base::RefCountedThreadSafe<Buffer> {
  public:
@@ skipping 38 matching lines @@
 }
 
 // Generates GUID which can be used to trace buffer using an Id.
 GPU_EXPORT base::trace_event::MemoryAllocatorDumpGuid GetBufferGUIDForTracing(
     uint64_t tracing_process_id,
     int32_t buffer_id);
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_BUFFER_H_