GitLab

Reverting per the original change description.

> [temporary M30 fix] Disable dragging tabs with web contents modal dialogs displayed
> 
> The full fix for the crashes in the associated bugs in trunk is too
> risky to merge into M30. After discussions among kareng and sky, the
> best approach was to disable dragging of tabs while a web contents modal
> dialog is displayed, to prevent the crashes. This only affects Chrome
> OS and will be reverted after testing in Canary and merging to the
> branch.
> 
> BUG=275274, 274856
> R=sky@chromium.org
> 
> Review URL: https://codereview.chromium.org/23698003

TBR=wittman@chromium.org
BUG=281831

Review URL: https://codereview.chromium.org/23814008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221834 0039d316-1c4b-4281-b951-d872f2087c98