[Android] Move LoadUrl from Tab upstream.

BUG=350016
TBR=thakis@chromium.org

Review URL: https://codereview.chromium.org/177013006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255636 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255636