gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/gles2_implementation.h

Index: gpu/command_buffer/client/gles2_implementation.h
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 102bd66abc10a34e5d12223262fc56e59df6b4f0..02948e9b8381dade21f571bd60978e103bab1821 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -591,6 +591,16 @@ class GLES2_IMPL_EXPORT GLES2Implementation
 
   void OnSwapBuffersComplete();
 
+  // Free transfer buffer if unused token already passed, or free pending
+  // the unused token if not.
+  void FreeTransferBuffer(BufferTracker::Buffer* buffer);
+
+  // Insert async token. In the GLES2 command buffer, is implemented to
+  // enumerate and synchronize asynchronous pixel uploads.
+  void InsertAsyncPixelUnpackToken(BufferTracker::Buffer *buffer);
+
+  void MarkPixelTransferBufferLastUsage(BufferTracker::Buffer* buffer);
+
   bool GetBoundPixelTransferBuffer(
       GLenum target, const char* function_name, GLuint* buffer_id);
   BufferTracker::Buffer* GetBoundPixelUnpackTransferBufferIfValid(