Offset scissor and viewport when using SetDrawRectangle on surface.

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 91cfbb27fb9d04297777aa168f2cc54bd1bce9e2..857a4ef8cf418646c217853f2b9b745811dcde7a 100644
--- a/ui/gl/gl_surface_stub.cc
+++ b/ui/gl/gl_surface_stub.cc
@@ -39,6 +39,14 @@ GLSurfaceFormat GLSurfaceStub::GetFormat() {
   return GLSurfaceFormat();
 }
 
+bool GLSurfaceStub::SupportsSetDrawRectangle() const {
+  return supports_draw_rectangle_;
+}
+
+gfx::Vector2d GLSurfaceStub::GetDrawOffset() const {
+  return supports_draw_rectangle_ ? gfx::Vector2d(100, 200) : gfx::Vector2d();
+}
+
 GLSurfaceStub::~GLSurfaceStub() {}
 
 }  // namespace gl