Let WebRTC notification not show "touch to return" in custom tab

Let WebRTC notification not show "touch to return" in custom tab

If the WebRTC is initiated from a custom tab, there is no way to return
to the tab by clicking the notification. This CL fixes the string
discrepency by removing it.

BUG=524855
Committed: https://crrev.com/6f074dddc0a530ead7658a082da76b0de4c0075c
Cr-Commit-Position: refs/heads/master@{#348031}

[Ian Wen, 2015-09-09 22:08:52]

ianwen@chromium.org changed reviewers:
+ dfalcantara@chromium.org

[Ian Wen, 2015-09-09 22:08:52]

PTAL.

[gone, 2015-09-09 22:10:59]

lgtm

[Ian Wen, 2015-09-09 22:16:06]

The CQ bit was checked by ianwen@chromium.org

[commit-bot: I haz the power, 2015-09-09 22:16:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327193004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327193004/1

[commit-bot: I haz the power, 2015-09-09 22:58:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-09 22:59:06]

Patchset 1 (id:??) landed as
https://crrev.com/6f074dddc0a530ead7658a082da76b0de4c0075c
Cr-Commit-Position: refs/heads/master@{#348031}

[commit-bot: I haz the power, 2015-09-23 12:04:32]

Patchset 1 (id:??) landed as
https://crrev.com/6f074dddc0a530ead7658a082da76b0de4c0075c
Cr-Commit-Position: refs/heads/master@{#348031}