Exempt the Service Thread from BLOCK_SHUTDOWN DCHECKs

base/task_scheduler/task_tracker.h

 // Copyright 2016 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.
 
 #ifndef BASE_TASK_SCHEDULER_TASK_TRACKER_H_
 #define BASE_TASK_SCHEDULER_TASK_TRACKER_H_
 
 #include <memory>
 
 #include "base/atomicops.h"
 #include "base/base_export.h"
 #include "base/callback_forward.h"
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_base.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/task_scheduler/scheduler_lock.h"
 #include "base/task_scheduler/sequence.h"
 #include "base/task_scheduler/task.h"
 #include "base/task_scheduler/task_traits.h"
 
 namespace base {
 
@@ skipping 50 matching lines @@
   // Causes HasShutdownStarted() to return true. Unlike when Shutdown() returns,
   // IsShutdownComplete() won't return true after this returns. Shutdown()
   // cannot be called after this.
   void SetHasShutdownStartedForTesting();
 
  protected:
   // Runs |task|. An override is expected to call its parent's implementation
   // but is free to perform extra work before and after doing so.
   virtual void PerformRunTask(std::unique_ptr<Task> task);
 
+#if DCHECK_IS_ON()
+  // Returns true if this context should be exempt from blocking shutdown
+  // DCHECKs.
+  // TODO(robliao): Remove when http://crbug.com/698140 is fixed.
+  virtual bool IsExemptFromBlockingShutdownChecks();
+#endif
+
  private:
   class State;
 
   void PerformShutdown();
 
   // Called before WillPostTask() informs the tracing system that a task has
   // been posted. Updates |num_tasks_blocking_shutdown_| if necessary and
   // returns true if the current shutdown state allows the task to be posted.
   bool BeforePostTask(TaskShutdownBehavior shutdown_behavior);
 
@@ skipping 55 matching lines @@
   // Number of BLOCK_SHUTDOWN tasks posted during shutdown.
   HistogramBase::Sample num_block_shutdown_tasks_posted_during_shutdown_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(TaskTracker);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_TASK_TRACKER_H_