Cache GL's viewport on the GPU command buffer client side.

gpu/command_buffer/client/client_context_state.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.
 
 #include "gpu/command_buffer/client/client_context_state.h"
 
+#include "base/logging.h"
+
 namespace gpu {
 namespace gles2 {
 
 ClientContextState::ClientContextState() {
 }
 
 ClientContextState::~ClientContextState() {
 }
 
+void ClientContextState::SetViewport(
+    GLint x, GLint y, GLsizei width, GLsizei height) {
+  DCHECK_LE(0, width);
+  DCHECK_LE(0, height);
+
+  viewport_x = x;
+  viewport_y = y;
+  viewport_width = width;
+  viewport_height = height;
+}
+
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/client/client_context_state_impl_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu