[NTP] Adding mathp@chromium.org as owner of NTP-related code

Specifically, the local NTP resources and the C++ code related to serving it (skipping over search and instant stuff).

BUG=None

Review URL: https://codereview.chromium.org/444593005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287610 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/local_ntp/OWNERS

 jered@chromium.org
 jeremycho@chromium.org
 samarth@chromium.org
+mathp@chromium.org

chrome/browser/search/OWNERS

@@ -4,3 +4,4 @@ jered@chromium.org
 samarth@chromium.org
 
 per-file hotword*=rlp@chromium.org
+per-file *source*=mathp@chromium.org