[DevTools] Fix undocked DevToolsWindow closing.

[DevTools] Fix undocked DevToolsWindow closing.

Test will follow in next patch, as it requires testing code refactoring.

BUG=393566, 393855
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283345

[dgozman, 2014-07-15 10:43:17]

Take a look please.

[pfeldman, 2014-07-15 10:49:27]

lgtm

[dgozman, 2014-07-15 11:08:27]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2014-07-15 11:11:09]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dgozman@chromium.org/395793003/1

[commit-bot: I haz the power, 2014-07-15 20:31:57]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-07-16 04:58:25]

Change committed as 283345