[Extensions] Add feature documentation for contexts

[Extensions] Add feature documentation for contexts

BUG=639162
Committed: https://crrev.com/06d4e588176fbf92ad9fb74e38da9b1a62dd3911
Cr-Commit-Position: refs/heads/master@{#414518}

[Devlin, 2016-08-23 23:21:32]

rdevlin.cronin@chromium.org changed reviewers:
+ asargent@chromium.org, lazyboy@chromium.org

[Devlin, 2016-08-23 23:21:33]

asargent + lazyboy, mind taking a look?

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
File chrome/common/extensions/api/_features.md (right):

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
chrome/common/extensions/api/_features.md:305: it's own domain, and these should
only be run within an extension process. Thus,
lazyboy@, can you confirm this is true?

[lazyboy, 2016-08-24 17:48:26]

lgtm

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
File chrome/common/extensions/api/_features.md (right):

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
chrome/common/extensions/api/_features.md:282: extension contexts. With site
isolation, extension frames running in web pages
link to "site isolation" ->
https://www.chromium.org/developers/design-documents/site-isolation

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
chrome/common/extensions/api/_features.md:305: it's own domain, and these should
only be run within an extension process. Thus,
On 2016/08/23 23:21:33, Devlin wrote:
> lazyboy@, can you confirm this is true?

Yes.

[Devlin, 2016-08-25 17:12:58]

Antony, anything missing from this?

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
File chrome/common/extensions/api/_features.md (right):

https://codereview.chromium.org/2268173003/diff/1/chrome/common/extensions/ap...
chrome/common/extensions/api/_features.md:282: extension contexts. With site
isolation, extension frames running in web pages
On 2016/08/24 17:48:26, lazyboy wrote:
> link to "site isolation" ->
> https://www.chromium.org/developers/design-documents/site-isolation

Done.

[asargent_no_longer_on_chrome, 2016-08-25 17:44:37]

lgtm

https://codereview.chromium.org/2268173003/diff/20001/chrome/common/extension...
File chrome/common/extensions/api/_features.md (right):

https://codereview.chromium.org/2268173003/diff/20001/chrome/common/extension...
chrome/common/extensions/api/_features.md:307: these have similar privilege
levels to blessed extension processes.
It's probably out-of-scope for this documentation, but I'd be interested in an
explanation of why we need to have an extension_service_worker context that is
distinct from blessed_extension.

Maybe I'll just ask lazyboy@ in person :)

[Devlin, 2016-08-25 18:37:41]

https://codereview.chromium.org/2268173003/diff/20001/chrome/common/extension...
File chrome/common/extensions/api/_features.md (right):

https://codereview.chromium.org/2268173003/diff/20001/chrome/common/extension...
chrome/common/extensions/api/_features.md:307: these have similar privilege
levels to blessed extension processes.
On 2016/08/25 17:44:37, Antony Sargent wrote:
> It's probably out-of-scope for this documentation, but I'd be interested in an
> explanation of why we need to have an extension_service_worker context that is
> distinct from blessed_extension.
> 
> Maybe I'll just ask lazyboy@ in person :)

I think I requested this because there are times when we might need this to be
distinct.  In particular, blessed_extension everywhere else refers to a context
that has a frame/window, and runs in the same process and on the same thread as
every other blessed_extension context (in the same extension). It's those
criteria that it make it possible for things like
chrome.runtime.getBackgroundPage() (which returns the DOM 'window' object for
the background page) possible - but that's fundamentally impossible for a
service worker context (where it could never synchronously access a window
object).  As such, there are potentially always going to be APIs that can run in
"normal" blessed_extension contexts, but not extension_service_worker contexts -
and this was an easy way to differentiate.

It could be that in the future, we switch this to something else (maybe a
separate property, restrict to x), but this was less overhead at the time. :)

[Devlin, 2016-08-25 18:38:54]

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

[Devlin, 2016-08-25 18:38:55]

The patchset sent to the CQ was uploaded after l-g-t-m from lazyboy@chromium.org
Link to the patchset: https://codereview.chromium.org/2268173003/#ps20001
(title: "linkify")

[Devlin, 2016-08-25 18:39:01]

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

[Devlin, 2016-08-25 19:00:15]

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

[Devlin, 2016-08-25 19:00:15]

The patchset sent to the CQ was uploaded after l-g-t-m from
asargent@chromium.org, lazyboy@chromium.org
Link to the patchset: https://codereview.chromium.org/2268173003/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2016-08-25 19:01:03]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-25 20:13:34]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-08-25 20:14:50]

Description was changed from

==========
[Extensions] Add feature documentation for contexts

BUG=639162
==========

to

==========
[Extensions] Add feature documentation for contexts

BUG=639162

Committed: https://crrev.com/06d4e588176fbf92ad9fb74e38da9b1a62dd3911
Cr-Commit-Position: refs/heads/master@{#414518}
==========

[commit-bot: I haz the power, 2016-08-25 20:14:56]

Patchset 3 (id:??) landed as
https://crrev.com/06d4e588176fbf92ad9fb74e38da9b1a62dd3911
Cr-Commit-Position: refs/heads/master@{#414518}