cc: DCHECK if SDOS::SwapBuffersComplete is called prematurely

cc/scheduler/scheduler.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.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
+#include "base/debug/stack_trace.h"
 #include "base/logging.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/single_thread_task_runner.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/scheduler/delay_based_time_source.h"
 
 namespace cc {
@@ skipping 199 matching lines @@
   state_machine_.DidSwapBuffers();
 
   // There is no need to call ProcessScheduledActions here because
   // swapping should not trigger any new actions.
   if (!inside_process_scheduled_actions_) {
     DCHECK_EQ(state_machine_.NextAction(), SchedulerStateMachine::ACTION_NONE);
   }
 }
 
 void Scheduler::DidSwapBuffersComplete() {
-  DCHECK_GT(state_machine_.pending_swaps(), 0) << AsValue()->ToString();
+  DCHECK_GT(state_machine_.pending_swaps(), 0)
+      << AsValue()->ToString() << base::debug::StackTrace().ToString();
   state_machine_.DidSwapBuffersComplete();
   ProcessScheduledActions();
 }
 
 void Scheduler::SetImplLatencyTakesPriority(bool impl_latency_takes_priority) {
   state_machine_.SetImplLatencyTakesPriority(impl_latency_takes_priority);
   ProcessScheduledActions();
 }
 
 void Scheduler::NotifyReadyToCommit() {
@@ skipping 580 matching lines @@
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
           state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 }
 
 }  // namespace cc