Fix a DCHECK failure by registering a handler for 'dialogClose' message.

Fix a DCHECK failure by registering a handler for 'dialogClose' message.

This fixes a DCHECK failure on chrome://print, where no handler was
registered to handle chrome.send("dialogClose").

BUG=416783
Committed: https://crrev.com/60d2c270d92b1510c8a371d653ad1a6f7f41326b
Cr-Commit-Position: refs/heads/master@{#297199}

[babu, 2014-09-29 08:48:57]

sudarsana.nagineni@intel.com changed reviewers:
+ estade@chromium.org

[Evan Stade, 2014-09-29 15:27:19]

lgtm

[babu, 2014-09-29 15:31:18]

The CQ bit was checked by sudarsana.nagineni@intel.com

[commit-bot: I haz the power, 2014-09-29 15:32:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/614683002/1

[commit-bot: I haz the power, 2014-09-29 17:30:16]

Committed patchset #1 (id:1) as d68bf7cc32706ffdf5c71b078246a964d53189e2

[commit-bot: I haz the power, 2014-09-29 17:31:32]

Patchset 1 (id:??) landed as
https://crrev.com/60d2c270d92b1510c8a371d653ad1a6f7f41326b
Cr-Commit-Position: refs/heads/master@{#297199}