Update chrome.identity API documentation to mention best practices.

Update chrome.identity API documentation to mention best practices.

This adds a tip on best practices to the documentation for getAuthToken,
and also updates the tip on launchWebAuthFlow to correct an inaccuracy.

BUG=372279
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274184

[Michael Courage, 2014-05-29 17:16:51]

ltm

[benwells, 2014-05-29 20:44:04]

On 2014/05/29 17:16:51, Michael Courage wrote:
> ltm

Did you miss a g?

[Michael Courage, 2014-05-29 20:46:14]

lgtm

i did

[benwells, 2014-05-29 21:27:37]

The CQ bit was checked by benwells@chromium.org

[commit-bot: I haz the power, 2014-05-29 21:29:12]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/benwells@chromium.org/305843003/40001

[commit-bot: I haz the power, 2014-05-30 00:58:00]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/18...)

[commit-bot: I haz the power, 2014-05-30 01:21:48]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-30 01:21:48]

Try jobs failed on following builders:
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/18...)

[benwells, 2014-06-02 06:27:46]

The CQ bit was checked by benwells@chromium.org

[commit-bot: I haz the power, 2014-06-02 06:27:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/benwells@chromium.org/305843003/40001

[commit-bot: I haz the power, 2014-06-02 08:02:23]

Change committed as 274184