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

gpu/ipc/service/gpu_command_buffer_stub.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.
 
 #include "gpu/ipc/service/gpu_command_buffer_stub.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 811 matching lines @@
   if (channel_->watchdog()) {
     executor_->SetCommandProcessedCallback(base::Bind(
         &GpuCommandBufferStub::OnCommandProcessed, base::Unretained(this)));
   }
 
   const size_t kSharedStateSize = sizeof(CommandBufferSharedState);
   if (!shared_state_shm->Map(kSharedStateSize)) {
     DLOG(ERROR) << "Failed to map shared state buffer.";
     return false;
   }
+  const int kImportance = 2;
+  shared_state_shm->set_importance(kImportance);
   command_buffer_->SetSharedStateBuffer(MakeBackingFromSharedMemory(
       std::move(shared_state_shm), kSharedStateSize));
 
   if (offscreen && !active_url_.is_empty())
     manager->delegate()->DidCreateOffscreenContext(active_url_);
 
   if (use_virtualized_gl_context_) {
     // If virtualized GL contexts are in use, then real GL context state
     // is in an indeterminate state, since the GLStateRestorer was not
     // initialized at the time the GLContextVirtual was made current. In
@@ skipping 164 matching lines @@
   TRACE_EVENT0("gpu", "GpuCommandBufferStub::OnRegisterTransferBuffer");
 
   // Take ownership of the memory and map it into this process.
   // This validates the size.
   std::unique_ptr<base::SharedMemory> shared_memory(
       new base::SharedMemory(transfer_buffer, false));
   if (!shared_memory->Map(size)) {
     DVLOG(0) << "Failed to map shared memory.";
     return;
   }
-
+  const int kImportance = 2;
+  shared_memory->set_importance(kImportance);
   if (command_buffer_) {
     command_buffer_->RegisterTransferBuffer(
         id, MakeBackingFromSharedMemory(std::move(shared_memory), size));
   }
 }
 
 void GpuCommandBufferStub::OnDestroyTransferBuffer(int32_t id) {
   TRACE_EVENT0("gpu", "GpuCommandBufferStub::OnDestroyTransferBuffer");
 
   if (command_buffer_)
@@ skipping 232 matching lines @@
       command_buffer_->GetLastState().error == error::kLostContext)
     return;
 
   command_buffer_->SetContextLostReason(error::kUnknown);
   if (decoder_)
     decoder_->MarkContextLost(error::kUnknown);
   command_buffer_->SetParseError(error::kLostContext);
 }
 
 }  // namespace gpu