Docs: devtools extensions. Messaging flow from inject script to devtools

Docs: devtools extensions. Messaging flow from inject script to devtools
Patch authored by: Thomas Boyt
http://www.thomasboyt.com/2014/10/06/chrome-message-workaround.html

BUG=

Committed: https://crrev.com/094e637503ebe258c4c94f67bd45939f9fbf51bd
Cr-Commit-Position: refs/heads/master@{#299853}

[paulirish, 2014-10-06 19:44:11]

paulirish@chromium.org changed reviewers:
+ mkearney@chromium.org

[paulirish, 2014-10-06 19:44:28]

PTAL

[paulirish, 2014-10-07 21:14:11]

paulirish@chromium.org changed reviewers:
+ pbakaus@chromium.org
- mkearney@chromium.org

[paulirish, 2014-10-07 21:14:28]

Can I get your review?

[paulirish, 2014-10-07 21:14:29]

Can I get your review?

[pbakaus, 2014-10-08 12:00:50]

lgtm

[paulirish, 2014-10-15 21:36:57]

The CQ bit was checked by paulirish@chromium.org

[commit-bot: I haz the power, 2014-10-15 21:37:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/632793002/1

[commit-bot: I haz the power, 2014-10-15 21:37:36]

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

[commit-bot: I haz the power, 2014-10-15 21:37:36]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[paulirish, 2014-10-15 21:38:23]

paulirish@chromium.org changed reviewers:
+ kalman@chromium.org

[paulirish, 2014-10-15 21:38:36]

kalman, rubber stamp from a committer requested! :)

[not at google - send to devlin, 2014-10-15 22:25:48]

lgtm

[paulirish, 2014-10-16 05:21:08]

The CQ bit was checked by paulirish@chromium.org

[commit-bot: I haz the power, 2014-10-16 05:21:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/632793002/1

[commit-bot: I haz the power, 2014-10-16 05:43:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-16 05:44:15]

Patchset 1 (id:??) landed as
https://crrev.com/094e637503ebe258c4c94f67bd45939f9fbf51bd
Cr-Commit-Position: refs/heads/master@{#299853}