Add FBO support in Android WebView

ui/gl/gl_surface_stub.cc

Index: ui/gl/gl_surface_stub.cc
diff --git a/ui/gl/gl_surface_stub.cc b/ui/gl/gl_surface_stub.cc
index a27d2af6aba688565304b6b4a009f8d4c159f4de..cb3e16467684910350aa5298778fd0371f68794b 100644
--- a/ui/gl/gl_surface_stub.cc
+++ b/ui/gl/gl_surface_stub.cc
@@ -4,8 +4,19 @@
 
 #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() {
 }
 
@@ -13,6 +24,10 @@ bool GLSurfaceStub::IsOffscreen() {
   return false;
 }
 
+unsigned int GLSurfaceStub::GetBackingFrameBufferObject() {
+  return fbo_;
+}
+
 bool GLSurfaceStub::SwapBuffers() {
   return true;
 }