Gallery: Fix enterMode.

Gallery: Fix binding of toggleMode method.

Previously the first argument of toggleMode function passed to the event handler
was not bounded. Thus event object is passed to the first argument of toggleMode
unintentionally.

BUG=447519
TEST=None

Committed: https://crrev.com/93321f0483086cb20aa9eb2ce9ab1b383f28e8c7
Cr-Commit-Position: refs/heads/master@{#310757}

[hirono, 2015-01-09 11:05:37]

Patchset #3 (id:40001) has been deleted

[hirono, 2015-01-09 11:05:45]

Patchset #2 (id:20001) has been deleted

[hirono, 2015-01-09 11:05:53]

Patchset #1 (id:1) has been deleted

[hirono, 2015-01-09 11:06:21]

hirono@chromium.org changed reviewers:
+ mtomasz@chromium.org

[hirono, 2015-01-09 11:06:21]

PTAL, thanks!

[mtomasz, 2015-01-09 11:30:27]

lgtm

[hirono, 2015-01-09 11:38:39]

The CQ bit was checked by hirono@chromium.org

[commit-bot: I haz the power, 2015-01-09 11:39:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/839173003/60001

[commit-bot: I haz the power, 2015-01-09 11:42:57]

Committed patchset #1 (id:60001)

[commit-bot: I haz the power, 2015-01-09 11:43:42]

Patchset 1 (id:??) landed as
https://crrev.com/93321f0483086cb20aa9eb2ce9ab1b383f28e8c7
Cr-Commit-Position: refs/heads/master@{#310757}