cc: Post the missed BeginFrame to a new stack

cc/surfaces/display_scheduler.cc

Index: cc/surfaces/display_scheduler.cc
diff --git a/cc/surfaces/display_scheduler.cc b/cc/surfaces/display_scheduler.cc
index d26d1b6306973debcf5abde447dfa0c928b981f7..7c662340948954c78eb9cb9696df358819b6cd28 100644
--- a/cc/surfaces/display_scheduler.cc
+++ b/cc/surfaces/display_scheduler.cc
@@ -97,7 +97,12 @@ void DisplayScheduler::SurfaceDamaged(const SurfaceId& surface_id) {
 
   if (!output_surface_lost_ && !observing_begin_frame_source_) {
     observing_begin_frame_source_ = true;
+    // When we call AddObserver() this will cause a missed BeginFrame to
+    // occur. We need to detect this and not process it immediately in the
+    // same call stack.
+    inside_add_observer_ = true;

[sunnyps, 2016/07/27 02:00:14]

nit: base::AutoReset<bool> mark_inside(&inside_add_observer_, true)

[danakj, 2016/07/27 02:19:04]

Done.

     begin_frame_source_->AddObserver(this);
+    inside_add_observer_ = false;
   }
 
   ScheduleBeginFrameDeadline();
@@ -138,6 +143,24 @@ bool DisplayScheduler::OnBeginFrameDerivedImpl(const BeginFrameArgs& args) {
   TRACE_EVENT2("cc", "DisplayScheduler::BeginFrame", "args", args.AsValue(),
                "now", now);
 
+  if (inside_add_observer_) {
+    // Repost this so that we don't run a missed BeginFrame on the same
+    // callstack. Otherwise we end up running unexpected scheduler actions
+    // immediately while inside some other action (such as submitting a frame
+    // for a SurfaceFactory).
+    DCHECK_EQ(args.type, BeginFrameArgs::MISSED);
+    DCHECK(missed_begin_frame_task_.IsCancelled());
+    missed_begin_frame_task_.Reset(base::Bind(
+        base::IgnoreResult(&DisplayScheduler::OnBeginFrameDerivedImpl),
+        weak_ptr_factory_.GetWeakPtr(), args));
+    task_runner_->PostTask(FROM_HERE, missed_begin_frame_task_.callback());
+    return true;
+  } else {
+    // If we get another BeginFrame before a posted missed frame, just drop the
+    // missed frame.
+    missed_begin_frame_task_.Cancel();
+  }
+
   // If we get another BeginFrame before the previous deadline,
   // synchronously trigger the previous deadline before progressing.
   if (inside_begin_frame_deadline_interval_) {