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

gpu/command_buffer/client/transfer_buffer.cc

 // 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.
 
 // A class to Manage a growing transfer buffer.
 
 #include "gpu/command_buffer/client/transfer_buffer.h"
 
 #include <stddef.h>
 #include <stdint.h>
@@ skipping 78 matching lines @@
 }
 
 unsigned int TransferBuffer::GetSize() const {
   return HaveBuffer() ? ring_buffer_->GetLargestFreeOrPendingSize() : 0;
 }
 
 unsigned int TransferBuffer::GetFreeSize() const {
   return HaveBuffer() ? ring_buffer_->GetTotalFreeSizeNoWaiting() : 0;
 }
 
+base::SharedMemory* TransferBuffer::GetSharedMemory() const {
+  if (!HaveBuffer())
+    return nullptr;
+  if (!buffer_->backing())
+    return nullptr;
+  return buffer_->backing()->shared_memory();
+}
+
 void TransferBuffer::AllocateRingBuffer(unsigned int size) {
   for (;size >= min_buffer_size_; size /= 2) {
     int32_t id = -1;
     scoped_refptr<gpu::Buffer> buffer =
         helper_->command_buffer()->CreateTransferBuffer(size, &id);
     if (id != -1) {
       DCHECK(buffer.get());
       buffer_ = buffer;
       ring_buffer_.reset(new RingBuffer(
           alignment_,
@@ skipping 106 matching lines @@
   Release();
   // NOTE: we allocate buffers of size 0 so that HaveBuffer will be true, so
   // that address will return a pointer just like malloc, and so that GetShmId
   // will be valid. That has the side effect that we'll insert a token on free.
   // We could add code skip the token for a zero size buffer but it doesn't seem
   // worth the complication.
   buffer_ = transfer_buffer_->AllocUpTo(new_size, &size_);
 }
 
 }  // namespace gpu