Remove registration in toolbar_view.cc for unused notification.

Remove registration in toolbar_view.cc for unused notification.

This was causing a DCHECK as ToolbarView::Observe both didn't handle the
asked-for notification and DCHECKed on unhandled notification types.

BUG=407124
TEST=NONE

Committed: https://crrev.com/2fa6c2ffe35e700a4529e1119954dc60faccf708
Cr-Commit-Position: refs/heads/master@{#291823}

[robertshield, 2014-08-25 15:16:51]

Hi Peter, I hit a DCHECK for what appears to be an unused notification in
toolbar_view.cc while running trunk chrome. 

This should fix the DCHECK, please take a look and let me know if it looks right
to you.

[Peter Kasting, 2014-08-25 18:51:16]

LGTM

[robertshield, 2014-08-25 21:01:22]

The CQ bit was checked by robertshield@chromium.org

[commit-bot: I haz the power, 2014-08-25 21:01:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/robertshield@chromium.org/503783002/1

[commit-bot: I haz the power, 2014-08-25 22:31:14]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_x64_rel_swarming on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-25 23:21:03]

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

[commit-bot: I haz the power, 2014-08-25 23:21:04]

Try jobs failed on following builders:
  win_chromium_x64_rel_swarming on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[robertshield, 2014-08-26 02:11:54]

The CQ bit was checked by robertshield@chromium.org

[commit-bot: I haz the power, 2014-08-26 02:12:41]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/robertshield@chromium.org/503783002/1

[commit-bot: I haz the power, 2014-08-26 02:52:39]

Committed patchset #1 (1) as 637a242848bda9364a97072f233c2696d9aa492e

[commit-bot: I haz the power, 2014-09-10 02:39:49]

Patchset 1 (id:??) landed as
https://crrev.com/2fa6c2ffe35e700a4529e1119954dc60faccf708
Cr-Commit-Position: refs/heads/master@{#291823}