[cc] Fix CompositorFrameSinkSupport BeginFrameAck interface.

components/exo/surface.cc

Index: components/exo/surface.cc
diff --git a/components/exo/surface.cc b/components/exo/surface.cc
index bdcd746536ddccae9d57dc5d578742f4868d6c1b..049c3c6070378bf1512e0e5a437d23e41ccb0de0 100644
--- a/components/exo/surface.cc
+++ b/components/exo/surface.cc
@@ -838,7 +838,17 @@ void Surface::UpdateSurface(bool full_damage) {
   quad_state->opacity = state_.alpha;
 
   cc::CompositorFrame frame;
-  current_begin_frame_ack_.has_damage = true;
+  // If we commit while we don't have an active BeginFrame, we acknowledge a
+  // manual one.
+  if (current_begin_frame_ack_.sequence_number ==
+      cc::BeginFrameArgs::kInvalidFrameNumber) {
+    current_begin_frame_ack_ =
+        cc::BeginFrameAck(cc::BeginFrameArgs::kManualSourceId,
+                          cc::BeginFrameArgs::kStartingFrameNumber,
+                          cc::BeginFrameArgs::kStartingFrameNumber, 0, true);
+  } else {
+    current_begin_frame_ack_.has_damage = true;
+  }
   frame.metadata.begin_frame_ack = current_begin_frame_ack_;
 
   if (current_resource_.id) {