Ensure that performance.memory is updated on first access.

Ensure that performance.memory is updated on first access.

A platform's implementation of monotonicallyIncreasingTime() is only
required to be non-decreasing over time. Hence when checking if memory
usage info should be updated for the first time, do not assume the
function returns a value that will trigger the initial update.

R=haraken
BUG=454380
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189339

[sof, 2015-02-02 13:43:52]

sigbjornf@opera.com changed reviewers:
+ haraken@chromium.org, jochen@chromium.org, tonyg@chromium.org

[sof, 2015-02-02 13:43:52]

Please take a look.

An issue that Opera has run into on some platform embeddings; not an issue with
supported platforms and clocks not set near Epoch.

[haraken, 2015-02-02 13:57:15]

LGTM

[sof, 2015-02-02 14:05:52]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-02-02 14:06:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/893803003/1

[commit-bot: I haz the power, 2015-02-02 14:51:08]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=189339