Do not block all task manager tree view mouse release events.
Do not block all task manager tree view mouse release events.

BUG=16974
TEST=you can resize rows of the task manager

Review URL: http://codereview.chromium.org/155670

git-svn-id: http://src.chromium.org/svn/trunk/src@21006 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: d8cc4016112e7490ce4154adacba71590430ec38
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser