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

gpu/command_buffer/client/mapped_memory.h

 // Copyright (c) 2012 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_CLIENT_MAPPED_MEMORY_H_
 #define GPU_COMMAND_BUFFER_CLIENT_MAPPED_MEMORY_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 11 matching lines @@
 class CommandBufferHelper;
 
 // Manages a shared memory segment.
 class GPU_EXPORT MemoryChunk {
  public:
   MemoryChunk(int32_t shm_id,
               scoped_refptr<gpu::Buffer> shm,
               CommandBufferHelper* helper);
   ~MemoryChunk();
 
+  gpu::Buffer* buffer() {
+    return shm_.get();
+  }
+
   // Gets the size of the largest free block that is available without waiting.
   unsigned int GetLargestFreeSizeWithoutWaiting() {
     return allocator_.GetLargestFreeSize();
   }
 
   // Gets the size of the largest free block that can be allocated if the
   // caller can wait.
   unsigned int GetLargestFreeSizeWithWaiting() {
     return allocator_.GetLargestFreeOrPendingSize();
   }
@@ skipping 231 matching lines @@
   uint32_t shm_offset_;
   bool flush_after_release_;
   CommandBufferHelper* helper_;
   MappedMemoryManager* mapped_memory_manager_;
   DISALLOW_COPY_AND_ASSIGN(ScopedMappedMemoryPtr);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_MAPPED_MEMORY_H_