Add Satisfy() and Require() to MojoCompositorFrameSink

cc/surfaces/compositor_frame_sink_support.cc

Index: cc/surfaces/compositor_frame_sink_support.cc
diff --git a/cc/surfaces/compositor_frame_sink_support.cc b/cc/surfaces/compositor_frame_sink_support.cc
index 011d9a091583d27ac07bb3598771baae74a3fc0a..4cd83354e60aeb706bcb1c287d7819450eb88ff3 100644
--- a/cc/surfaces/compositor_frame_sink_support.cc
+++ b/cc/surfaces/compositor_frame_sink_support.cc
@@ -8,6 +8,7 @@
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/compositor_frame_sink_support_client.h"
 #include "cc/surfaces/display.h"
+#include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_manager.h"
 
 namespace cc {
@@ -78,6 +79,19 @@ void CompositorFrameSinkSupport::SubmitCompositorFrame(
   }
 }
 
+void CompositorFrameSinkSupport::Require(const LocalFrameId& local_frame_id,
+                                         const SurfaceSequence& sequence) {
+  Surface* surface = surface_manager_->GetSurfaceForId(
+      SurfaceId(frame_sink_id_, local_frame_id));
+  DCHECK(surface);  // Ensure the surface exists before requiring callback

[Fady Samuel, 2016/12/06 16:45:25]

nit: How about this comment? 

If this fails then that implies that a client is trying to reference a surface
that no longer exists. This could result in flicker or missing components of UI.

[Alex Z., 2016/12/06 16:55:40]

Done.

+  surface->AddDestructionDependency(sequence);
+}
+
+void CompositorFrameSinkSupport::Satisfy(const SurfaceSequence& sequence) {
+  std::vector<uint32_t> sequences = {sequence.sequence};
+  surface_manager_->DidSatisfySequences(sequence.frame_sink_id, &sequences);
+}
+
 void CompositorFrameSinkSupport::DidReceiveCompositorFrameAck() {
   DCHECK_GT(ack_pending_count_, 0);
   ack_pending_count_--;