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

gpu/command_buffer/common/buffer.cc

 // Copyright 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.
 
 #include "gpu/command_buffer/common/buffer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
 
 namespace gpu {
 
-bool BufferBacking::is_shared() const {
-  return false;
+base::SharedMemory* BufferBacking::shared_memory() {
+  return nullptr;
 }
 
 SharedMemoryBufferBacking::SharedMemoryBufferBacking(
     std::unique_ptr<base::SharedMemory> shared_memory,
     size_t size)
     : shared_memory_(std::move(shared_memory)), size_(size) {}
 
 SharedMemoryBufferBacking::~SharedMemoryBufferBacking() {}
 
-bool SharedMemoryBufferBacking::is_shared() const {
-  return true;
+base::SharedMemory* SharedMemoryBufferBacking::shared_memory() {
+  return shared_memory_.get();
 }
 
 void* SharedMemoryBufferBacking::GetMemory() const {
   return shared_memory_->memory();
 }
 
 size_t SharedMemoryBufferBacking::GetSize() const { return size_; }
 
 Buffer::Buffer(std::unique_ptr<BufferBacking> backing)
     : backing_(std::move(backing)),
@@ skipping 27 matching lines @@
 }
 
 base::trace_event::MemoryAllocatorDumpGuid GetBufferGUIDForTracing(
     uint64_t tracing_process_id,
     int32_t buffer_id) {
   return base::trace_event::MemoryAllocatorDumpGuid(base::StringPrintf(
       "gpu-buffer-x-process/%" PRIx64 "/%d", tracing_process_id, buffer_id));
 }
 
 } // namespace gpu