[cc] Set BeginFrame sequence numbers on CompositorFrames from Scheduler.

cc/scheduler/scheduler_state_machine.h

Index: cc/scheduler/scheduler_state_machine.h
diff --git a/cc/scheduler/scheduler_state_machine.h b/cc/scheduler/scheduler_state_machine.h
index 0b2a0ebf7818699306f3050a39a90f6e2c1e4496..b3014a9f6be7c1ff718476796dc71830ebb88d4e 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -279,6 +279,9 @@ class CC_EXPORT SchedulerStateMachine {
   bool did_submit_in_last_frame() const { return did_submit_in_last_frame_; }
 
   uint32_t begin_frame_source_id() const { return begin_frame_source_id_; }
+  uint64_t last_begin_frame_sequence_number_active_tree_was_fresh() const {
+    return last_begin_frame_sequence_number_active_tree_was_fresh_;
+  }
   uint64_t last_begin_frame_sequence_number_compositor_frame_was_fresh() const {
     return last_begin_frame_sequence_number_compositor_frame_was_fresh_;
   }