cc: Toward merging DrawFrame and SwapBuffers in DelegatingRenderer.

cc/output/delegating_renderer_unittest.cc

Index: cc/output/delegating_renderer_unittest.cc
diff --git a/cc/output/delegating_renderer_unittest.cc b/cc/output/delegating_renderer_unittest.cc
index 87fd7b6db8dd8021063ed55d9709ff24d92e6cb3..235802bf6552946972e38d1424866aa91c81412e 100644
--- a/cc/output/delegating_renderer_unittest.cc
+++ b/cc/output/delegating_renderer_unittest.cc
@@ -24,9 +24,13 @@ class DelegatingRendererTestDraw : public DelegatingRendererTest {
 
   void AfterTest() override {}
 
-  void DrawLayersOnThread(LayerTreeHostImpl* host_impl) override {
+  DrawResult PrepareToDrawOnThread(LayerTreeHostImpl* host_impl,
+                                   LayerTreeHostImpl::FrameData* frame_data,
+                                   DrawResult draw_result) override {
+    EXPECT_EQ(DRAW_SUCCESS, draw_result);
     EXPECT_EQ(0, num_swaps_);
     drawn_viewport_ = host_impl->DeviceViewport();
+    return draw_result;
   }
 
   void DisplayReceivedCompositorFrameOnThread(