Reland "Add new latency_info for tracking browser composite time."

content/browser/renderer_host/compositor_impl_android.cc

Index: content/browser/renderer_host/compositor_impl_android.cc
diff --git a/content/browser/renderer_host/compositor_impl_android.cc b/content/browser/renderer_host/compositor_impl_android.cc
index f1fced07b898bffc533c9bbc5a3d6e054a6059d6..81ad1751015df22e88e4d5454d90b82ecb543380 100644
--- a/content/browser/renderer_host/compositor_impl_android.cc
+++ b/content/browser/renderer_host/compositor_impl_android.cc
@@ -81,6 +81,11 @@ class OutputSurfaceWithoutParent : public cc::OutputSurface {
   }
 
   virtual void SwapBuffers(cc::CompositorFrame* frame) override {
+    for (auto& latency : frame->metadata.latency_info) {
+      latency.AddLatencyNumber(
+          ui::INPUT_EVENT_BROWSER_SWAP_BUFFER_COMPONENT, 0, 0);

[jdduke (slow), 2015/01/06 16:01:43]

Hmm, I actually don't see this component used anywhere. The deadline estimation
only uses BROWSER_COMPOSITE_COMPONENT and GPU_SWAP_BUFFER_COMPONENT. Can we get
rid of this?

+    }
+
     GetCommandBufferProxy()->SetLatencyInfo(frame->metadata.latency_info);
     DCHECK(frame->gl_frame_data->sub_buffer_rect ==
            gfx::Rect(frame->gl_frame_data->size));