Add Sync related APIs to GPU command buffer: Part I

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 730171de6251af172f8bb2e97daca3f0509c6645..a1b3621b380a73ecdf2bc2516c72cfa30a181d9c 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -478,6 +478,7 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   void DeleteSamplersHelper(GLsizei n, const GLuint* samplers);
   void DeleteTransformFeedbacksHelper(
       GLsizei n, const GLuint* transformfeedbacks);
+  void DeleteSyncHelper(GLsync sync);
 
   void DeleteBuffersStub(GLsizei n, const GLuint* buffers);
   void DeleteFramebuffersStub(GLsizei n, const GLuint* framebuffers);
@@ -490,6 +491,7 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   void DeleteSamplersStub(GLsizei n, const GLuint* samplers);
   void DeleteTransformFeedbacksStub(
       GLsizei n, const GLuint* transformfeedbacks);
+  void DeleteSyncStub(GLsizei n, const GLuint* syncs);
 
   void BufferDataHelper(
       GLenum target, GLsizeiptr size, const void* data, GLenum usage);