Add FBO support in Android WebView

ui/gl/gl_surface_stub.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 "ui/gl/gl_surface_stub.h"
 
+#include "ui/gl/gl_bindings.h"
+
 namespace gfx {
 
+GLSurfaceStub::GLSurfaceStub() : fbo_(0) {}
+
+void GLSurfaceStub::SaveCurrentFBO() {
+  GLint fbo = 0;
+  glGetIntegerv(GL_FRAMEBUFFER_BINDING_EXT, &fbo);
+  DCHECK_GE(fbo, 0);
+  fbo_ = static_cast<unsigned int>(fbo);
+}
+
 void GLSurfaceStub::Destroy() {
 }
 
 bool GLSurfaceStub::IsOffscreen() {
   return false;
 }
 
+unsigned int GLSurfaceStub::GetBackingFrameBufferObject() {
+  return fbo_;
+}
+
 bool GLSurfaceStub::SwapBuffers() {
   return true;
 }
 
 gfx::Size GLSurfaceStub::GetSize() {
   return size_;
 }
 
 void* GLSurfaceStub::GetHandle() {
   return NULL;
 }
 
 GLSurfaceStub::~GLSurfaceStub() {}
 
 }  // namespace gfx