Clamp resolution of requestIdleCallback timeRemaining() to 5us.

third_party/WebKit/Source/core/dom/IdleDeadline.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/dom/IdleDeadline.h"
 
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 IdleDeadline::IdleDeadline(double deadlineSeconds, CallbackType callbackType)
     : m_deadlineSeconds(deadlineSeconds)
     , m_callbackType(callbackType)
 {
 }
 
 double IdleDeadline::timeRemaining() const
 {
     double timeRemaining = m_deadlineSeconds - monotonicallyIncreasingTime();
     if (timeRemaining < 0)
         timeRemaining = 0;
 
-    return timeRemaining * 1000;
+    const double resolutionSeconds = 0.000005;

[esprehn, 2015/09/24 21:33:06]

This is just duplicating what performance.now does, can we just call whatever
that calls? All timers in the engine should probably clamp to this...

[rmcilroy, 2015/09/24 22:53:18]

Good idea, added PerformanceBase::clampTimeResolution for this (happy to move
this if you have a suggestion for a better location).
By this do you mean the likes of PerformanceTimer, PerformanceUserTiming,
ResourceTimingInfo, etc? Ilya: would this work from a spec point of view? If so
I can do this in a followup CL.

+    return 1000.0 * floor(timeRemaining / resolutionSeconds) * resolutionSeconds;
 }
 
 } // namespace blink