Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

gpu/command_buffer/client/gles2_implementation.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.
 
 // A class to emulate GLES2 over command buffers.
 
 #include "../client/gles2_implementation.h"
 
 #include <map>
 #include <set>
@@ skipping 3241 matching lines @@
   if (bound_element_array_buffer_id_ == 0) {
     // Restore the element array binding.
     helper_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
   }
 #else
   helper_->DrawElementsInstancedANGLE(
       mode, count, type, ToGLuint(indices), primcount);
 #endif
 }
 
+void GLES2Implementation::DiscardBackbufferCHROMIUM() {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << this << "] glDiscardBackbufferCHROMIUM()");
+  helper_->DiscardBackbufferCHROMIUM();
+  helper_->CommandBufferHelper::Flush();
+}
+
+void GLES2Implementation::EnsureBackbufferCHROMIUM() {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << this << "] glEnsureBackbufferCHROMIUM()");
+  helper_->EnsureBackbufferCHROMIUM();
+}
+
 }  // namespace gles2
 }  // namespace gpu