Add maximum screen size into constraint for webkitGetuserMedia()

BUG=509002
Added maxWidth:screen.width and maxHeight:screen.height constrains for video in webkitGetUserMedia().Therefore, the stream may have higher resolution than 640*480 which is default in webkitGetUserMedia().

Committed: https://crrev.com/709188caa73363b653f67c990c5705c26d4fe9bf
Cr-Commit-Position: refs/heads/master@{#351118}

[GeorgeZ, 2015-08-26 23:56:58]

gyzhou@chromium.org changed reviewers:
+ niklase@chromium.org

[GeorgeZ, 2015-08-26 23:59:03]

Please review it for me.

[Niklas Enbom, 2015-08-27 16:36:04]

lgtm, please:
- Change the issue title to describe exactly what the code changes are doing,
something like "Add screen size parameters as resolution constraint"
- Run try bots using git cl try
- add mkearney as OWNER reviewer, he has reviewed this file in the past

On 2015/08/26 23:59:03, GeorgeZ wrote:
> Please review it for me.

[GeorgeZ, 2015-08-27 16:49:23]

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

[GeorgeZ, 2015-08-27 17:03:25]

On 2015/08/27 16:36:04, Niklas Enbom wrote:
> lgtm, please:
> - Change the issue title to describe exactly what the code changes are doing,
> something like "Add screen size parameters as resolution constraint"
> - Run try bots using git cl try
> - add mkearney as OWNER reviewer, he has reviewed this file in the past
> 
> On 2015/08/26 23:59:03, GeorgeZ wrote:
> > Please review it for me.

I followed the instruction and will publish+mail comments one more time to
include mkearney as OWNER for review

[GeorgeZ, 2015-08-27 17:04:27]

mkearney,

Please have a review for me.

Thanks,

George

[gyzhou, 2015-09-28 17:32:48]

The CQ bit was checked by gyzhou@google.com

[commit-bot: I haz the power, 2015-09-28 17:37:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1321453004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1321453004/1

[commit-bot: I haz the power, 2015-09-28 17:37:55]

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-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.

[gyzhou, 2015-09-28 17:48:48]

On 2015/09/28 17:37:55, commit-bot: I haz the power wrote:
> No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
> Even if an L-G-T-M may have been provided, it was from a non-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.

mkearney,

I need your approve to submit this CL. 

Thanks,

George

[mkearney1, 2015-09-28 18:07:45]

The CQ bit was checked by mkearney@chromium.org

[mkearney1, 2015-09-28 18:07:45]

lgtm

[commit-bot: I haz the power, 2015-09-28 18:10:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1321453004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1321453004/1

[gyzhou, 2015-09-28 18:23:29]

The CQ bit was unchecked by gyzhou@google.com

[gyzhou, 2015-09-28 18:23:51]

The CQ bit was checked by gyzhou@google.com

[commit-bot: I haz the power, 2015-09-28 18:29:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1321453004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1321453004/1

[commit-bot: I haz the power, 2015-09-28 19:38:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-28 19:39:44]

Patchset 1 (id:??) landed as
https://crrev.com/709188caa73363b653f67c990c5705c26d4fe9bf
Cr-Commit-Position: refs/heads/master@{#351118}