cc: Do not reset pending tree state incorrectly on aborted commits.

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/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 560 matching lines @@
   DCHECK(visible_);
   DCHECK(!begin_frame_source_paused_);
   DCHECK(!send_begin_main_frame_funnel_);
   begin_main_frame_state_ = BEGIN_MAIN_FRAME_STATE_SENT;
   needs_begin_main_frame_ = false;
   send_begin_main_frame_funnel_ = true;
   last_frame_number_begin_main_frame_sent_ = current_frame_number_;
 }
 
 void SchedulerStateMachine::WillCommit(bool commit_has_no_updates) {
+  DCHECK(!has_pending_tree_ ||
+         (settings_.main_frame_before_activation_enabled &&
+          commit_has_no_updates));
   commit_count_++;
 
   if (commit_has_no_updates || settings_.main_frame_before_activation_enabled) {
     begin_main_frame_state_ = BEGIN_MAIN_FRAME_STATE_IDLE;
   } else {
     begin_main_frame_state_ = BEGIN_MAIN_FRAME_STATE_WAITING_FOR_ACTIVATION;
   }
 
   // If the commit was aborted, then there is no pending tree.

[enne (OOO), 2016/05/16 17:05:41]

I don't think this comment is true any longer.

[sunnyps, 2016/05/16 19:54:22]

Done.

-  has_pending_tree_ = !commit_has_no_updates;
+  if (!commit_has_no_updates)
+    has_pending_tree_ = true;
 
   wait_for_ready_to_draw_ =
       !commit_has_no_updates && settings_.commit_to_active_tree;
 
   // Update state related to forced draws.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT) {
     forced_redraw_state_ = has_pending_tree_
                                ? FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION
                                : FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
   }
@@ skipping 534 matching lines @@
     case OUTPUT_SURFACE_ACTIVE:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
       return true;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace cc