[Extensions] Precede api enums with an '_' if the first character is a digit

[Extensions] Precede api enums with an '_' if the first character is a digit

If the first character of an extension api enum is a digit (we know that the
enums can only be composed of a-zA-Z0-9_ now), then precede it with a digit
so that people can do chrome.fooApi._345_CRAZY_ENUM.

BUG=463184
Committed: https://crrev.com/bba416f4bad7fccd508a09a21dc23c503e28cdca
Cr-Commit-Position: refs/heads/master@{#327198}

[Devlin, 2015-04-27 23:03:19]

rdevlin.cronin@chromium.org changed reviewers:
+ kalman@chromium.org

[Devlin, 2015-04-27 23:03:19]

We don't (yet) have any enums quite this crazy, so no test added, but I checked
it by adding a bogus enum locally and it works.

[not at google - send to devlin, 2015-04-27 23:05:02]

lgtm. remember we need to document this stuff.

[Devlin, 2015-04-27 23:05:58]

On 2015/04/27 23:05:02, kalman wrote:
> lgtm. remember we need to document this stuff.

Yep. Wanted to make sure we have everything in place before we tell people to
use it. ;)

Any other edge cases you can think of that we need to cover?

[Devlin, 2015-04-27 23:06:23]

rdevlin.cronin@chromium.org changed reviewers:
+ stevenjb@chromium.org

[Devlin, 2015-04-27 23:06:33]

+Steven as FYI.

[Devlin, 2015-04-27 23:06:45]

rdevlin.cronin@chromium.org changed reviewers:
- stevenjb@chromium.org

[Devlin, 2015-04-27 23:06:49]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2015-04-27 23:07:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1107223002/1

[commit-bot: I haz the power, 2015-04-28 00:50:09]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-28 00:50:53]

Patchset 1 (id:??) landed as
https://crrev.com/bba416f4bad7fccd508a09a21dc23c503e28cdca
Cr-Commit-Position: refs/heads/master@{#327198}