cc: Allow sending BeginMainFrame before draw or activation

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 8dbf82925ca49d7f772cb0424e3257d65fdefec2..40a054f119ba50154ec4d08a6bfc175342bdc535 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -63,6 +63,7 @@ class CC_EXPORT SchedulerStateMachine {
     COMMIT_STATE_BEGIN_MAIN_FRAME_SENT,
     COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED,
     COMMIT_STATE_READY_TO_COMMIT,
+    COMMIT_STATE_WAITING_FOR_ACTIVATION,
     COMMIT_STATE_WAITING_FOR_FIRST_DRAW,
   };
   static const char* CommitStateToString(CommitState state);
@@ -100,6 +101,7 @@ class CC_EXPORT SchedulerStateMachine {
            commit_state_ == COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED ||
            commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
   }
+  CommitState commit_state() const { return commit_state_; }
 
   bool RedrawPending() const { return needs_redraw_; }
   bool ManageTilesPending() const { return needs_manage_tiles_; }
@@ -231,6 +233,9 @@ class CC_EXPORT SchedulerStateMachine {
   void NotifyReadyToActivate();
 
   bool has_pending_tree() const { return has_pending_tree_; }
+  bool active_tree_needs_first_draw() const {
+    return active_tree_needs_first_draw_;
+  }
 
   void DidManageTiles();
   void DidLoseOutputSurface();
@@ -242,8 +247,6 @@ class CC_EXPORT SchedulerStateMachine {
 
   bool SupportsProactiveBeginImplFrame() const;
 
-  CommitState commit_state() const { return commit_state_; }
-
  protected:
   bool BeginImplFrameNeededToDraw() const;
   bool ProactiveBeginImplFrameWanted() const;