Expected Queueing Time Metric ignores tasks with nested message loops.

third_party/WebKit/public/platform/scheduler/base/task_time_observer.h

Index: third_party/WebKit/public/platform/scheduler/base/task_time_observer.h
diff --git a/third_party/WebKit/public/platform/scheduler/base/task_time_observer.h b/third_party/WebKit/public/platform/scheduler/base/task_time_observer.h
index 6f8c89c5c3b7b883d70d577fa6cb2defd0f283b1..f742dc577e46d5dd4d15de6e4aa6d8140d3f3d6f 100644
--- a/third_party/WebKit/public/platform/scheduler/base/task_time_observer.h
+++ b/third_party/WebKit/public/platform/scheduler/base/task_time_observer.h
@@ -32,6 +32,9 @@ class BLINK_PLATFORM_EXPORT TaskTimeObserver {
                               double start_time,
                               double end_time) = 0;
 
+  // Callback to be called when we enter a nested message loop.
+  virtual void onBeginNestedMessageLoop() = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(TaskTimeObserver);
 };