Prevents reentrant CompleteDrag when changing display configuration

Prevent reentrant CompleteDrag when changing display configuration

BUG=315395
TEST=interactive_ui_tests --gtest_filter=*CancelDragTabToWindowIn*Display

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=233541

[varkha, 2013-11-06 02:24:03]

oshima@, can you please take a look? This is another issue revealed by tests
when enabling docked windows by default. The test specified in the CL will
detect the crash when docking behavior is enabled (in CL
https://codereview.chromium.org/55363004/) so I didn't think this warranted a
separate test. Essentially any reparenting during CompleteDrag or RevertDrag
assumed that the scoped resizer would be reset to NULL before the call so that
we don't call it more than once. This was done properly in some handlers and not
in some other handlers, most notably display configuration handler.

[oshima, 2013-11-06 02:58:44]

lgtm

[commit-bot: I haz the power, 2013-11-06 03:29:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/varkha@chromium.org/61443002/1

[commit-bot: I haz the power, 2013-11-06 04:45:14]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[commit-bot: I haz the power, 2013-11-06 04:49:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/varkha@chromium.org/61443002/1

[commit-bot: I haz the power, 2013-11-06 08:46:37]

Retried try job too often on linux_chromeos for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_chro...

[commit-bot: I haz the power, 2013-11-06 13:29:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/varkha@chromium.org/61443002/1

[commit-bot: I haz the power, 2013-11-06 17:01:17]

Retried try job too often on linux_aura for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_aura...

[commit-bot: I haz the power, 2013-11-06 19:02:12]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/varkha@chromium.org/61443002/1

[commit-bot: I haz the power, 2013-11-07 08:04:59]

Change committed as 233541