Add LeakTracker<URLRequestContext> to IOThread::CleanUp().
Add LeakTracker<URLRequestContext> to IOThread::CleanUp().

Move LeakTracker<URLRequest> up to CleanUp also.  No URLRequest should be getting killed in DestructionObservers anymore.

BUG=59630
TEST=existing

Review URL: http://codereview.chromium.org/4064004

git-svn-id: http://src.chromium.org/svn/trunk/src@63651 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: ace23f60a028ef62087ecf0ea430f8f2aaea928d
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