[Webapp Refactor] Implements remoting.MessageDialog

[Webapp Refactor] Implements emoting.MessageDialog

This CL implements remoting.MessageBox, a helper class for
showing a modal dialog using remoting.setMode() and updates
the corresponding call sites to use it.

This enables us to show the Me2Me finish dialog from within
remoting.Me2MeActivity instead of the global event handlers. In
this way, we can move the reconnect after finish logic from
remoting.SessionConnector into remoting.Me2MeActivity in a future
CL.

BUG=474840
NOTRY=true
TESTS=All Remoting Webapp Unittests passes and all Chromoting integration test passes
https://chromium-swarm.appspot.com/user/task/26b396ab62998910

Committed: https://crrev.com/e474a782678b914c4d4095ee02dd3d693eb79906
Cr-Commit-Position: refs/heads/master@{#324282}

[kelvinp, 2015-04-08 01:05:19]

kelvinp@chromium.org changed reviewers:
+ jamiewalch@chromium.org

[kelvinp, 2015-04-08 01:15:56]

PTAL

[kelvinp, 2015-04-08 17:59:39]

Patchset #3 (id:40001) has been deleted

[kelvinp, 2015-04-08 17:59:45]

Patchset #2 (id:20001) has been deleted

[kelvinp, 2015-04-08 17:59:51]

Patchset #1 (id:1) has been deleted

[Jamie, 2015-04-08 20:07:29]

https://codereview.chromium.org/1066283002/diff/60001/remoting/webapp/base/js...
File remoting/webapp/base/js/input_dialog.js (left):

https://codereview.chromium.org/1066283002/diff/60001/remoting/webapp/base/js...
remoting/webapp/base/js/input_dialog.js:93: })();
Did you intend to remove this? I don't see any changes for its call-sites.

[kelvinp, 2015-04-08 20:10:20]

PTAL

https://codereview.chromium.org/1066283002/diff/60001/remoting/webapp/base/js...
File remoting/webapp/base/js/input_dialog.js (left):

https://codereview.chromium.org/1066283002/diff/60001/remoting/webapp/base/js...
remoting/webapp/base/js/input_dialog.js:93: })();
On 2015/04/08 20:07:29, Jamie wrote:
> Did you intend to remove this? I don't see any changes for its call-sites.

This is renamed to modal_dialog.js as it now also includes the message dialogs.

[Jamie, 2015-04-08 20:12:53]

lgtm

[kelvinp, 2015-04-08 20:50:00]

The CQ bit was checked by kelvinp@chromium.org

[commit-bot: I haz the power, 2015-04-08 20:50:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1066283002/60001

[commit-bot: I haz the power, 2015-04-08 20:53:35]

Committed patchset #1 (id:60001)

[commit-bot: I haz the power, 2015-04-08 20:55:12]

Patchset 1 (id:??) landed as
https://crrev.com/e474a782678b914c4d4095ee02dd3d693eb79906
Cr-Commit-Position: refs/heads/master@{#324282}