Removing unecessary button label

Removing unecessary button label

Remove the Cancel button from the app banner infobar on desktop.

This makes the infobar consistent with the mobile implementation, which
only has an Accept button and a dismissal X.

BUG=491001
R=benwells

Committed: https://crrev.com/68736e1c6c8edec4d7c3627f815488fdd30e4263
Cr-Commit-Position: refs/heads/master@{#333720}

[dominickn (DO NOT USE), 2015-06-09 05:55:44]

dominickn@google.com changed reviewers:
+ dfalcantara@chromium.org
- benwells@chromium.org

[dominickn (DO NOT USE), 2015-06-09 05:56:26]

dominickn@google.com changed reviewers:
+ benwells@chromium.org
- dfalcantara@chromium.org

[benwells, 2015-06-10 04:14:11]

lgtm

[dominickn (DO NOT USE), 2015-06-10 11:03:08]

The CQ bit was checked by dominickn@google.com

[commit-bot: I haz the power, 2015-06-10 11:03:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163323004/1

[commit-bot: I haz the power, 2015-06-10 11:50:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-10 11:51:32]

Patchset 1 (id:??) landed as
https://crrev.com/68736e1c6c8edec4d7c3627f815488fdd30e4263
Cr-Commit-Position: refs/heads/master@{#333720}