cc: Emulate BeginFrame in OutputSurfaces that don't support it natively

cc/scheduler/scheduler_state_machine.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/scheduler/scheduler_state_machine.h"
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
 
 namespace cc {
@@ skipping 314 matching lines @@
   }
 }
 
 void SchedulerStateMachine::SetMainThreadNeedsLayerTextures() {
   DCHECK(!main_thread_needs_layer_textures_);
   DCHECK_NE(texture_state_, LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD);
   main_thread_needs_layer_textures_ = true;
 }
 
 bool SchedulerStateMachine::BeginFrameNeededByImplThread() const {
+  // We should proactively request a BeginFrame if a commit is pending.

[brianderson, 2013/06/01 04:30:29]

I would get hangs without this.

+  if (commit_state_ != COMMIT_STATE_IDLE)
+    return true;
+
   // If we have a pending tree, need to keep getting notifications until
   // the tree is ready to be swapped.
   if (has_pending_tree_)
     return true;
 
   // If we can't draw, don't tick until we are notified that we can draw again.
   if (!can_draw_)
     return false;
 
   if (needs_forced_redraw_)
@@ skipping 103 matching lines @@
 bool SchedulerStateMachine::HasInitializedOutputSurface() const {
   return output_surface_state_ == OUTPUT_SURFACE_ACTIVE;
 }
 
 void SchedulerStateMachine::SetMaximumNumberOfFailedDrawsBeforeDrawIsForced(
     int num_draws) {
   maximum_number_of_failed_draws_before_draw_is_forced_ = num_draws;
 }
 
 }  // namespace cc