Fix another typo in histograms.xml for the Settings.TrackedSplitPreferenceChanged field trial histogram...

NOTRY=True

Review URL: https://codereview.chromium.org/178373002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252958 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252958