Exempt the Service Thread from BLOCK_SHUTDOWN DCHECKs

base/task_scheduler/task_tracker.h

Index: base/task_scheduler/task_tracker.h
diff --git a/base/task_scheduler/task_tracker.h b/base/task_scheduler/task_tracker.h
index 14ca1f419329dc9cb890eab9e9693f5419d8d250..376bbf52df77befde1565939867868c2381a6303 100644
--- a/base/task_scheduler/task_tracker.h
+++ b/base/task_scheduler/task_tracker.h
@@ -10,6 +10,7 @@
 #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"
@@ -80,6 +81,13 @@ class BASE_EXPORT TaskTracker {
   // 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 IsPostingBlockShutdownTaskAfterShutdownAllowed();
+#endif
+
  private:
   class State;