cc: Introduce BeginFrame sequence numbers and acknowledgements.

services/ui/ws/frame_generator.cc

Index: services/ui/ws/frame_generator.cc
diff --git a/services/ui/ws/frame_generator.cc b/services/ui/ws/frame_generator.cc
index fab8468381fce50de6854af8f50b306c9aeeb60d..cf22b062ed1d934707423e899448fa33ac0ec333 100644
--- a/services/ui/ws/frame_generator.cc
+++ b/services/ui/ws/frame_generator.cc
@@ -94,12 +94,14 @@ void FrameGenerator::OnSurfaceCreated(const cc::SurfaceId& surface_id,
 
 void FrameGenerator::DidReceiveCompositorFrameAck() {}
 
-void FrameGenerator::OnBeginFrame(const cc::BeginFrameArgs& begin_frame_arags) {
+void FrameGenerator::OnBeginFrame(const cc::BeginFrameArgs& begin_frame_args) {
   if (!root_window_->visible())
     return;
 
   // TODO(fsamuel): We should add a trace for generating a top level frame.
   cc::CompositorFrame frame(GenerateCompositorFrame(root_window_->bounds()));
+  frame.metadata.begin_frame_number = begin_frame_args.sequence_number;
+  frame.metadata.oldest_incorporated_frame = begin_frame_args.sequence_number;
 
   if (compositor_frame_sink_) {
     gfx::Size frame_size = last_submitted_frame_size_;