gpu: Defer reads from default framebuffer when needed.

gpu/command_buffer/client/gles2_implementation_impl_autogen.h

 // 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.
 
 // This file is auto-generated from
 // gpu/command_buffer/build_gles2_cmd_buffer.py
 // DO NOT EDIT!
 
 // This file is included by gles2_implementation.cc to define the
 // GL api functions.
@@ skipping 99 matching lines @@
     return GL_FRAMEBUFFER_UNSUPPORTED;
   }
   *result = 0;
   helper_->CheckFramebufferStatus(
       target, GetResultShmId(), GetResultShmOffset());
   WaitForCmd();
   GPU_CLIENT_LOG("returned " << *result);
   return *result;
 }
 
+void GLES2Implementation::Clear(GLbitfield mask) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClear(" << mask << ")");
+  helper_->Clear(mask);
+}
+
 void GLES2Implementation::ClearColor(
     GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClearColor(" << red << ", " << green << ", " << blue << ", " << alpha << ")");  // NOLINT
   helper_->ClearColor(red, green, blue, alpha);
 }
 
 void GLES2Implementation::ClearDepthf(GLclampf depth) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClearDepthf(" << depth << ")");
@@ skipping 1384 matching lines @@
 }
 
 void GLES2Implementation::TraceEndCHROMIUM() {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glTraceEndCHROMIUM(" << ")");
   helper_->TraceEndCHROMIUM();
 }
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_IMPL_AUTOGEN_H_