app_shell: Allow getUserMedia to select a capture device by id

app_shell: Allow getUserMedia to select a capture device by id

Return the device if it exists. Still return the first available device
if getUserMedia() doesn't ask for one in particular.

BUG=407236
TEST=manual

Committed: https://crrev.com/df30065ad5553de910e9d955be5ecb9362f6245f
Cr-Commit-Position: refs/heads/master@{#292061}

[James Cook, 2014-08-26 23:48:58]

jamescook@chromium.org changed reviewers:
+ derat@chromium.org

[James Cook, 2014-08-26 23:48:58]

Dan, PTAL. It turns out Hangouts requests the camera/mic by ID (even if there is
only one) so we need to support that.

[Daniel Erat, 2014-08-27 00:01:33]

lgtm

[James Cook, 2014-08-27 00:02:27]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-08-27 00:03:19]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamescook@chromium.org/514463002/1

[commit-bot: I haz the power, 2014-08-27 01:12:00]

Committed patchset #1 (1) as 9f58c64b00bfb41fec24ae193598df28cd106ff8

[commit-bot: I haz the power, 2014-09-10 02:48:29]

Patchset 1 (id:??) landed as
https://crrev.com/df30065ad5553de910e9d955be5ecb9362f6245f
Cr-Commit-Position: refs/heads/master@{#292061}