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

ui/gfx/gpu_memory_buffer.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 UI_GFX_GPU_MEMORY_BUFFER_H_
 #define UI_GFX_GPU_MEMORY_BUFFER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 84 matching lines @@
 
   // Returns a platform specific handle for this buffer.
   virtual GpuMemoryBufferHandle GetHandle() const = 0;
 
   // Type-checking downcast routine.
   virtual ClientBuffer AsClientBuffer() = 0;
 
   // Returns the GUID for tracing.
   virtual base::trace_event::MemoryAllocatorDumpGuid GetGUIDForTracing(
       uint64_t tracing_process_id) const;
+
+  virtual base::SharedMemory* GetSharedMemory();
 };
 
 // Returns an instance of |handle| which can be sent over IPC. This duplicates
 // the file-handles as appropriate, so that the IPC code take ownership of them,
 // without invalidating |handle| itself.
 GFX_EXPORT GpuMemoryBufferHandle
 CloneHandleForIPC(const GpuMemoryBufferHandle& handle);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GPU_MEMORY_BUFFER_H_