commit 3d256ea09ce900c796386c41c0afc59fd4a344b0
author Edwin Joe <ejoe@google.com> Tue Apr 23 21:24:38 2019
committer Commit Bot <commit-bot@chromium.org> Tue Apr 23 21:24:38 2019
tree d6bcbc1220d05b7e2d12988c57e37c4fc54e62a9
parent 2e9940c49fab7261750827b3ad35185925071aae

Added a PausableElapsedTimer.

There are some cases where an elapsed timer that can be paused is
useful.

An example case is recording surface embedding time to UMA metric.
Currently, the surface embedding time is recorded by simply taking
the different between the TimeTicks of the surface id allocation time
and the TimeTicks of when Surface::OnWillBeDrawn is called.
However, it is possible that surface id is allocated when the Renderer
is not visible, i.e. when the child changes size while hidden.
In this case, the surface embedding time will be arbitrarily inflated
since Surface::OnWillBeDrawn will not be called until it becomes
visible.

By using a pausable elapsed timer, the surface embedding time can be
paused if the renderer is hidden, and resumed when it becomes visible
again.

Bug: 949967
Change-Id: Ide8e5b67a06bae7d3ca1352574c477f35e32369c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1576331
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Edwin Joe <ejoe@google.com>
Cr-Commit-Position: refs/heads/master@{#653372}