Add chrome-custom-fit to instant watchlist

Bug: None
Change-Id: I2918bedb89b3f8682d7fa5d5fdfabab06f6d56bb
Reviewed-on: https://chromium-review.googlesource.com/c/1311873
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Reviewed-by: Ramya Nagarajan <ramyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604451}

WATCHLISTS

@@ -2212,7 +2212,8 @@
                 'kmadhusu+watch@chromium.org',
                 'melevin+watch@chromium.org',
                 'samarth+watch@chromium.org',
-                'skanuj+watch@chromium.org'],
+                'skanuj+watch@chromium.org',
+                'chrome-custom-fit+reviews@google.com'],
     'ios': ['ios-reviews@chromium.org'],
     'ios_chrome': ['ios-reviews+chrome@chromium.org',
                    'noyau+watch@chromium.org',