Edited comments for NESTABLE_ASYNC events

Edited comments for NESTABLE_ASYNC events

The documentation for NESTABLE_ASYNC events is not quite right. It does not say
that we use "id" to match events, and it is not accurate about the parsing rule
for unmatched events. This CL makes changes to the comments, so it will be
clearer to future users of the API.

Committed: https://crrev.com/f84110e6fe66416fa79a9b3136c1ee5a02941e43
Cr-Commit-Position: refs/heads/master@{#320952}

[xunjieli, 2015-03-17 16:20:07]

Patchset #1 (id:1) has been deleted

[xunjieli, 2015-03-17 16:21:04]

xunjieli@chromium.org changed reviewers:
+ dsinclair@chromium.org, nduca@chromium.org

[dsinclair, 2015-03-17 17:51:29]

The CQ bit was checked by dsinclair@chromium.org

[dsinclair, 2015-03-17 17:51:30]

lgtm

[commit-bot: I haz the power, 2015-03-17 17:52:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1016753003/20001

[commit-bot: I haz the power, 2015-03-17 19:12:11]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-03-17 19:13:03]

Patchset 1 (id:??) landed as
https://crrev.com/f84110e6fe66416fa79a9b3136c1ee5a02941e43
Cr-Commit-Position: refs/heads/master@{#320952}