cc: Emulate BeginFrame in OutputSurfaces that don't support it natively

cc/test/layer_tree_test.h

Index: cc/test/layer_tree_test.h
diff --git a/cc/test/layer_tree_test.h b/cc/test/layer_tree_test.h
index 856caaae6c841d3c035fddd010c4b1a97b360c5d..2d67a44ed6dd6b01fb4a7e17582a8d2b53bac3e0 100644
--- a/cc/test/layer_tree_test.h
+++ b/cc/test/layer_tree_test.h
@@ -24,6 +24,7 @@ class LayerImpl;
 class LayerTreeHost;
 class LayerTreeHostClient;
 class LayerTreeHostImpl;
+class FakeOutputSurface;
 
 // Used by test stubs to notify the test when something interesting happens.
 class TestHooks : public WebKit::WebAnimationDelegate {
@@ -160,6 +161,7 @@ class LayerTreeTest : public testing::Test, public TestHooks {
   LayerTreeSettings settings_;
   scoped_ptr<LayerTreeHostClientForTesting> client_;
   scoped_ptr<LayerTreeHost> layer_tree_host_;
+  FakeOutputSurface* output_surface_;
 
   bool beginning_;
   bool end_when_begin_returns_;