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

gpu/command_buffer/client/gles2_implementation_unittest.cc

Index: gpu/command_buffer/client/gles2_implementation_unittest.cc
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest.cc b/gpu/command_buffer/client/gles2_implementation_unittest.cc
index fdfcd501bbbe5a3460197db37f63be6872b1a714..a5de48e60ddbffe522db80f4be31bdb7a207c860 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest.cc
+++ b/gpu/command_buffer/client/gles2_implementation_unittest.cc
@@ -149,6 +149,7 @@ class MockTransferBuffer : public TransferBufferInterface {
   void FreePendingToken(void* p, unsigned int /* token */) override;
   unsigned int GetSize() const override;
   unsigned int GetFreeSize() const override;
+  base::SharedMemory* GetSharedMemory() const override;
 
   size_t MaxTransferBufferSize() {
     return size_ - result_size_;
@@ -329,6 +330,10 @@ unsigned int MockTransferBuffer::GetFreeSize() const {
   return 0;
 }
 
+base::SharedMemory* MockTransferBuffer::GetSharedMemory() const {
+  return nullptr;
+}
+
 // API wrapper for Buffers.
 class GenBuffersAPI {
  public: