Move PerformanceBase to TaskRunnerTimer.

third_party/WebKit/Source/core/timing/PerformanceBase.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 48 matching lines @@
   return nullptr;
 }
 
 }  // namespace
 
 using PerformanceObserverVector = HeapVector<Member<PerformanceObserver>>;
 
 static const size_t defaultResourceTimingBufferSize = 150;
 static const size_t defaultFrameTimingBufferSize = 150;
 
-PerformanceBase::PerformanceBase(double timeOrigin)
+PerformanceBase::PerformanceBase(double timeOrigin,
+                                 RefPtr<WebTaskRunner> taskRunner)
     : m_frameTimingBufferSize(defaultFrameTimingBufferSize),
       m_resourceTimingBufferSize(defaultResourceTimingBufferSize),
       m_userTiming(nullptr),
       m_timeOrigin(timeOrigin),
       m_observerFilterOptions(PerformanceEntry::Invalid),
       m_deliverObservationsTimer(
+          std::move(taskRunner),

[haraken, 2017/01/20 02:21:51]

What is making it hard to unconditionally use
TaskRunnerHelper::get(TaskType::PerformanceTimeline) here?

[jbroman, 2017/01/20 02:27:04]

PerformanceBase doesn't have any object to pass to TaskRunnerHelper. And it's
the base class also of WorkerPerformance, so LocalFrame and Document don't
apply.

ExecutionContext could possibly be used, but we don't actually need the whole
ExecutionContext, and currently some of the test implementations return nullptr
from their override of getExecutionContext.
It seems better, then, to have the derived class be responsible for choosing the
arguments to pass to TaskRunnerHelper. The only subclass for which that's
currently very meaningful is Performance (the main-thread version).

           this,
           &PerformanceBase::deliverObservationsTimerFired) {}
 
 PerformanceBase::~PerformanceBase() {}
 
 PerformanceNavigationTiming::NavigationType PerformanceBase::getNavigationType(
     NavigationType type,
     const Document* document) {
   if (document &&
       document->pageVisibilityState() == PageVisibilityStatePrerender) {
@@ skipping 511 matching lines @@
   visitor->trace(m_resourceTimingBuffer);
   visitor->trace(m_navigationTiming);
   visitor->trace(m_userTiming);
   visitor->trace(m_observers);
   visitor->trace(m_activeObservers);
   visitor->trace(m_suspendedObservers);
   EventTargetWithInlineData::trace(visitor);
 }
 
 }  // namespace blink