De-dupe copy requests for tab capture in DelegatedFrameHost.

content/browser/renderer_host/render_widget_host_view_aura_unittest.cc

Index: content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc b/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
index 02045bd426780b3b34be506f02088016758469d8..fc101b5b15d6fc69a68aaea32bda1b8dc7281e4f 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
@@ -2112,8 +2112,12 @@ TEST_F(RenderWidgetHostViewAuraCopyRequestTest, DestroyedAfterCopyRequest) {
                              request->texture_mailbox(),
                              scoped_ptr<cc::SingleReleaseCallback>());
 
-  // This runs until the callback happens.
+  // Simulate a composite by running the loop and then notifying

[danakj, 2015/03/09 22:20:15]

Can you maybe add a test here that shows de-duping works?

[miu, 2015/03/10 02:50:43]

Done.

+  // DelegatedFrameHost that the graphics commands were issued.  The latter is
+  // required to clear the "frame subscriber de-duping" flag.
   run_loop.Run();
+  view_->GetDelegatedFrameHost()->OnCompositingStarted(nullptr,

[danakj, 2015/03/09 22:20:15]

Maybe you should OnCompositingEnded() here too, you know to match them.

[miu, 2015/03/10 02:50:43]

Done.

+                                                       base::TimeTicks::Now());
 
   // The callback should succeed.
   EXPECT_EQ(1, callback_count_);