Make sure scheduler shutdown prevents idle tasks from running

third_party/WebKit/Source/platform/scheduler/child/idle_helper.h

Index: third_party/WebKit/Source/platform/scheduler/child/idle_helper.h
diff --git a/third_party/WebKit/Source/platform/scheduler/child/idle_helper.h b/third_party/WebKit/Source/platform/scheduler/child/idle_helper.h
index 5cf7199f90084b38de7d92eea4f7482754818e96..5f0ccd7a182598f7c092feb79723a7680045d453 100644
--- a/third_party/WebKit/Source/platform/scheduler/child/idle_helper.h
+++ b/third_party/WebKit/Source/platform/scheduler/child/idle_helper.h
@@ -94,6 +94,9 @@ class BLINK_PLATFORM_EXPORT IdleHelper
       base::TimeDelta required_quiescence_duration_before_long_idle_period);
   ~IdleHelper() override;
 
+  // Prevents any further idle tasks from running.
+  void Shutdown();
+
   // Returns the idle task runner. Tasks posted to this runner may be reordered
   // relative to other task types and may be starved for an arbitrarily long
   // time if no idle time is available.
@@ -229,6 +232,8 @@ class BLINK_PLATFORM_EXPORT IdleHelper
 
   const char* disabled_by_default_tracing_category_;
 
+  bool is_shutdown_;
+
   base::WeakPtr<IdleHelper> weak_idle_helper_ptr_;
   base::WeakPtrFactory<IdleHelper> weak_factory_;