Re: [ResourceTiming] The clock base to use in ResourceTiming is not defined

On Fri, 2013-09-27 at 22:42 -0400, Boris Zbarsky wrote:
> This is implementor feedback on 
> http://www.w3c-test.org/webperf/specs/ResourceTiming/
> 
> This document never defines the point that corresponds to time 0. 

All the timing attributes are using the DOMHighResTimeStamp type, which
is defined in High Resolution Time as follows:
[[
4.2 The DOMHighResTimeStamp Type

The DOMHighResTimeStamp type is used to store a time value measured
relative to the navigationStart attribute of the PerformanceTiming
interface [NavigationTiming], the start of navigation of the document,
or a time value that represents a duration between two
DOMHighResTimeStamps.
]]
http://www.w3.org/TR/2012/REC-hr-time-20121217/#sec-DOMHighResTimeStamp

Therefore, unless the attribute represents a duration (such as
PerformanceEntry.duration), the 0 time is relative to navigationStart.
This helps prevent clock skew or adjustment of the system clock.

Philippe