Revert "Bug fix: TranferBufferManager's SharedMemory memory usage reporting was wrong"

gpu/command_buffer/common/buffer.h

Index: gpu/command_buffer/common/buffer.h
diff --git a/gpu/command_buffer/common/buffer.h b/gpu/command_buffer/common/buffer.h
index 6a0a0d28ef2d73d14984115970a46f2882ec0c65..475056e5d965cb07369903e7daab5fb24dce66e2 100644
--- a/gpu/command_buffer/common/buffer.h
+++ b/gpu/command_buffer/common/buffer.h
@@ -28,7 +28,6 @@ namespace gpu {
 class GPU_EXPORT BufferBacking {
  public:
   virtual ~BufferBacking() {}
-  virtual bool is_shared() const;
   virtual base::SharedMemoryHandle shared_memory_handle() const;
   virtual void* GetMemory() const = 0;
   virtual size_t GetSize() const = 0;
@@ -39,7 +38,6 @@ class GPU_EXPORT SharedMemoryBufferBacking : public BufferBacking {
   SharedMemoryBufferBacking(std::unique_ptr<base::SharedMemory> shared_memory,
                             size_t size);
   ~SharedMemoryBufferBacking() override;
-  bool is_shared() const override;
   base::SharedMemoryHandle shared_memory_handle() const override;
   void* GetMemory() const override;
   size_t GetSize() const override;