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..0d5b4ac893839ff8f181a75ce471a7d66c3c5b7d 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 +79,23 @@ 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));
+  if (!surface) {
+    LOG(ERROR) << "Attempting to require callback on nonexistent surface";

[danakj, 2016/12/06 00:08:17]

DLOG if you really want it. Strings are expensive to our binary size. This feels
like a "soft DCHECK", either this should happen sometimes or it shouldn't
normally. Which is this, or why is it more complicated?

[Fady Samuel, 2016/12/06 00:12:14]

If this happens then this is a bug. This means that we wantto retain a reference
to a surface that no longer exists. This means  we'll flicker at the very least
or parts of the UI will not show up.

[danakj, 2016/12/06 00:29:28]

Then DCHECK instead?

[Alex Z., 2016/12/06 15:52:09]

Done.

+    return;
+  }
+  surface->AddDestructionDependency(sequence);
+}
+
+void CompositorFrameSinkSupport::Satisfy(const SurfaceSequence& sequence) {
+  std::vector<uint32_t> sequences;

[danakj, 2016/12/06 00:08:17]

perviously i'd say construct this with size 1. but how about with an initializer
list instead?

std::vector<uint32_t> sequences = {sequence.sequence};

[Alex Z., 2016/12/06 15:52:09]

Done.

+  sequences.push_back(sequence.sequence);
+  surface_manager_->DidSatisfySequences(sequence.frame_sink_id, &sequences);
+}
+
 void CompositorFrameSinkSupport::DidReceiveCompositorFrameAck() {
   DCHECK_GT(ack_pending_count_, 0);
   ack_pending_count_--;