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

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index ee69188efb8c4566eb02583a0a8fa3f26709e1e2..4d457828378e6be10ad057c7a0f0825d58931898 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -787,4 +787,18 @@ bool Scheduler::IsBeginMainFrameSentOrStarted() const {
               SchedulerStateMachine::BEGIN_MAIN_FRAME_STATE_STARTED);
 }
 
+uint32_t Scheduler::CurrentBeginFrameSourceId() const {
+  return begin_main_frame_args_.source_id;
+}
+
+uint64_t Scheduler::CurrentBeginFrameSequenceNumber() const {
+  return begin_main_frame_args_.sequence_number;
+}
+
+uint64_t Scheduler::LatestConfirmedBeginFrameSequenceNumberForActiveTree()
+    const {
+  return state_machine_
+      .last_begin_frame_sequence_number_active_tree_was_fresh();
+}
+
 }  // namespace cc