Cleanup client plugin handling code in the webapp.

Cleanup client plugin handling code in the webapp.

Previously the <embed> element was created in client_session.js , while
it's owned by the ClientPlugin object. Moved plugin creation code where
it belongs, to client_plugin.js .

R=jamiewalch@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289323

[Jamie, 2014-08-12 21:58:55]

lgtm

[Sergey Ulanov, 2014-08-12 21:59:51]

The CQ bit was checked by sergeyu@chromium.org

[commit-bot: I haz the power, 2014-08-12 22:03:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sergeyu@chromium.org/469453003/1

[commit-bot: I haz the power, 2014-08-13 00:33:33]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tri...)
  win_chromium_x64_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-13 02:36:45]

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

[commit-bot: I haz the power, 2014-08-13 02:36:46]

Try jobs failed on following builders:
  android_dbg_triggered_tests on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tri...)

[Sergey Ulanov, 2014-08-13 17:00:04]

Committed patchset #1 manually as 289323 (presubmit successful).