Fix closure compiler in network_list.js.

Fix closure compiler in network_list.js.

The type of fist argument of createVPNConnectionCallback_ is "string=", which is "string|undefined". But the type of extensionID that is passed to the function is "string|null".

The CL adds "|| undefined" to the next of extensionID so that it replaces "null" type with "undefined".

BUG=None
TEST=None
TBR=pneubeck@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/e8caff36192c96c409acd97e610fd918e7848ea6

[hirono, 2015-03-20 03:28:28]

hirono@chromium.org changed reviewers:
+ pneubeck@chromium.org

[hirono, 2015-03-20 03:28:28]

@pneubeck - Let me TBR for the nit change.

[commit-bot: I haz the power, 2015-03-20 03:34:36]

Patchset 1 (id:??) landed as
https://crrev.com/e8caff36192c96c409acd97e610fd918e7848ea6
Cr-Commit-Position: refs/heads/master@{#321509}

[hirono, 2015-03-20 03:34:46]

Committed patchset #1 (id:1) manually as
e8caff36192c96c409acd97e610fd918e7848ea6 (presubmit successful).

[pneubeck (no reviews), 2015-03-20 08:23:06]

please explain what the compiler error was and why this fixes the problem.

[hirono, 2015-03-20 09:43:46]

On 2015/03/20 08:23:06, pneubeck wrote:
> please explain what the compiler error was and why this fixes the problem.

I updated the CL description. Thanks!