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 069384bdcccd4585a29e107c1e6f3ee5c3841b3a..a6b9f5da0dba7472d9c0e1721f917caf26d68150 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -61,7 +61,6 @@ class CC_EXPORT SchedulerStateMachine {
     COMMIT_STATE_IDLE,
     COMMIT_STATE_FRAME_IN_PROGRESS,
     COMMIT_STATE_READY_TO_COMMIT,
-    COMMIT_STATE_WAITING_FOR_FIRST_DRAW,

[enne (OOO), 2014/01/23 21:51:55]

I'm not sure I follow the removal of this state.  Can that be done in a separate
patch?

[brianderson, 2014/01/23 23:31:35]

At ToT, COMMIT_STATE_WAITING_FOR_FIRST_DRAW can be replaced with
(has_pending_tree_ || active_tree_needs_first_draw_), so removing it in a
separate patch would be pretty easy.

I included it in this patch because I needed to decouple draw scheduling from
commit scheduling. By default, this patch starts the next commit before drawing
the previous commit and we'd never enter this state. Commit throttling is done
implicitly now via has_pending_tree_, active_tree_needs_first_draw_, and the
current settings.

I suppose I could keep the state and add COMMIT_STATE_WAITING_FOR_ACTIVATION to
be explicit about what the commit is waiting for, but that would complicate the
state transition logic and encode redundant state with the has_pending_tree and
active_tree_needs_first_draw_ variables.

   };
   static const char* CommitStateToString(CommitState state);
 
@@ -97,6 +96,7 @@ class CC_EXPORT SchedulerStateMachine {
     return commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
            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_; }
@@ -224,6 +224,9 @@ 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();