Revert of Avoids releasing capture in EndMoveLoop if capture was switched to another...

Revert of Avoids releasing capture in EndMoveLoop if capture was switched to another window while dragging (https://codereview.chromium.org/265843004/)

Reason for revert:
Appears to be responsible for ash_unittests failing on Linux ChromiumOS Tests(1): http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%281%29/builds/43114

Original issue's description:
> Avoids releasing capture in EndMoveLoop if capture was switched to another window while dragging.
> This variant relies on checking if a drag input window still has capture before releasing the grab.
> A better alternative is in CL https://codereview.chromium.org/262893002/.
>
> BUG=363503
> TEST=Follow the exact steps in the bug description.
> TEST=interactive_ui_tests --gtest_filter=*TabDragging*
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=269593

TBR=sadrul@chromium.org,varkha@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=363503

Review URL: https://codereview.chromium.org/276163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269629 0039d316-1c4b-4281-b951-d872f2087c98