Force events to be non blocking if main thread is unresponsive.

third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h

Index: third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h
diff --git a/third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h b/third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h
index 21db2557f17485ea8c0dc6347c5ab92914f6d7b4..18ac433107dcf8cb42854b19105e042ace8377a2 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h
+++ b/third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.h
@@ -9,6 +9,8 @@
 #include "base/time/time.h"
 #include "public/platform/WebCommon.h"
 
+#include <memory>
+
 namespace base {
 class TickClock;
 }
@@ -33,10 +35,15 @@ class BLINK_PLATFORM_EXPORT QueueingTimeEstimator {
 
   QueueingTimeEstimator(Client* client, base::TimeDelta window_duration);
 
-  void OnToplevelTaskCompleted(base::TimeTicks task_start_time,
+  void OnTopLevelTaskStarted(base::TimeTicks task_start_time);
+  void OnTopLevelTaskCompleted(base::TimeTicks task_start_time,
                                base::TimeTicks task_end_time);
 
+  base::TimeDelta EstimateQueueingTimeIncludingCurrentTask(base::TimeTicks now) const;
+
  private:
+  // Returns a clone of this object, with the |client_| set to |client|.
+  std::unique_ptr<QueueingTimeEstimator> CloneWithClient(Client* client) const;

[Sami, 2016/08/24 14:56:01]

Is it necessary for this to be a heap allocation? It seems like we could make
this a private copy constructor and keep the temporary class on the stack.

Alternatively we could split the computation backend from the client reporting
part and only copy the former, but I'm not sure if it would be worth it.

[tdresser, 2016/08/24 17:22:50]

Done.

   bool TimePastWindowEnd(base::TimeTicks task_end_time);
   Client* client_;  // NOT OWNED.
 
@@ -44,6 +51,9 @@ class BLINK_PLATFORM_EXPORT QueueingTimeEstimator {
   base::TimeDelta window_duration_;
   base::TimeTicks window_start_time_;
 
+  // Only used when including active task in estimated queueing time.
+  base::TimeTicks current_task_start_time_;
+
   DISALLOW_COPY_AND_ASSIGN(QueueingTimeEstimator);
 };