Add one more test to TreeNodeModelTest.
Add one more test to TreeNodeModelTest.

This add a SetTitle test, so we can verify if the TreeNodeModelChanged is
properly called and the node is properly renamed.

BUG=None
TEST=out/Debug/app_unittests --gtest_filter=TreeNodeModelTest.SetTitle.

Review URL: http://codereview.chromium.org/3015059

git-svn-id: http://src.chromium.org/svn/trunk/src@55338 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: fdc289637c94c45874c704901a8f71e5bccf384d
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