Add missing app permissions to media stream examples

Add missing app permissions to media stream examples

For media_stream_audio example, add 'audioCapture' permission
For media_stream_video example, add 'videoCapture' permission

Missing these permissions will cause NavigatorUserMediaError

BUG=NONE
TEST=Build the app and load it into Chrome, you should see it's working.

Committed: https://crrev.com/4c33b2d569d4ddeec03b1984c4d35659293d0a4f
Cr-Commit-Position: refs/heads/master@{#351120}

[Sunny, 2015-09-27 08:52:53]

ratsunny@gmail.com changed reviewers:
+ sbc@chromium.org

[Sunny, 2015-09-27 09:24:36]

Hi everyone, could you help to review this patch? Thanks.

[sbc, 2015-09-28 17:13:29]

sbc@google.com changed reviewers:
+ sbc@google.com

[sbc, 2015-09-28 17:13:29]

lgtm

[Sunny, 2015-09-28 17:15:18]

The CQ bit was checked by ratsunny@gmail.com

[commit-bot: I haz the power, 2015-09-28 17:16:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1374513002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1374513002/1

[commit-bot: I haz the power, 2015-09-28 17:16:43]

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

[commit-bot: I haz the power, 2015-09-28 17:16:44]

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.

[Sam Clegg, 2015-09-28 17:18:26]

lgtm

[Sunny, 2015-09-28 17:19:33]

The CQ bit was checked by ratsunny@gmail.com

[commit-bot: I haz the power, 2015-09-28 17:20:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1374513002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1374513002/1

[commit-bot: I haz the power, 2015-09-28 19:40:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-28 19:40:48]

Patchset 1 (id:??) landed as
https://crrev.com/4c33b2d569d4ddeec03b1984c4d35659293d0a4f
Cr-Commit-Position: refs/heads/master@{#351120}