[Extensions UI Mac] Fix race condition in showing the icon surfacing bubble

[Extensions UI Mac] Fix race condition in showing the icon surfacing bubble

The toolbar icon surfacing bubble shows up the first time the user runs the
browser with the --extension-action-redesign feature.  There's a race condition
in the mac code where if the browser window starts up before the extension
system is ready, the code incorrectly infers that there are no new extensions,
and doesn't show the bubble.  Fix this, and add a test.

BUG=582512
Review URL: https://codereview.chromium.org/1643963003

Cr-Commit-Position: refs/heads/master@{#372410}
(cherry picked from commit 213c3cfdc605711c89dc202867241cd49badef98)

Committed: https://chromium.googlesource.com/chromium/src/+/0199dfd31a1b5c637819377c7b31f98b9ea1cb62

[Devlin, 2016-02-02 19:57:38]

Description was changed from

==========
[Extensions UI Mac] Fix race condition in showing the icon surfacing bubble

The toolbar icon surfacing bubble shows up the first time the user runs the
browser with the --extension-action-redesign feature.  There's a race condition
in the mac code where if the browser window starts up before the extension
system is ready, the code incorrectly infers that there are no new extensions,
and doesn't show the bubble.  Fix this, and add a test.

BUG=582512

Review URL: https://codereview.chromium.org/1643963003

Cr-Commit-Position: refs/heads/master@{#372410}
(cherry picked from commit 213c3cfdc605711c89dc202867241cd49badef98)
==========

to

==========
[Extensions UI Mac] Fix race condition in showing the icon surfacing bubble

The toolbar icon surfacing bubble shows up the first time the user runs the
browser with the --extension-action-redesign feature.  There's a race condition
in the mac code where if the browser window starts up before the extension
system is ready, the code incorrectly infers that there are no new extensions,
and doesn't show the bubble.  Fix this, and add a test.

BUG=582512

Review URL: https://codereview.chromium.org/1643963003

Cr-Commit-Position: refs/heads/master@{#372410}
(cherry picked from commit 213c3cfdc605711c89dc202867241cd49badef98)

Committed:
https://chromium.googlesource.com/chromium/src/+/0199dfd31a1b5c637819377c7b31...
==========

[Devlin, 2016-02-02 19:57:39]

Committed patchset #1 (id:1) manually as
0199dfd31a1b5c637819377c7b31f98b9ea1cb62.