Add self to Diagnostics app watchlist

Change-Id: Ie0c6060859a2a1b95301d55bee2ac788ee063ad1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2613561
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Auto-Submit: Gavin Williams <gavinwill@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840815}

WATCHLISTS

@@ -2479,6 +2479,7 @@
                        'odejesush+watch@chromium.org'],
     'devtools': ['devtools-reviews@chromium.org'],
     'diagnostics_ui': ['baileyberro+diagnostics-watch@chromium.org',
+                       'gavinwill+diagnostics-watch@chromium.org',
                        'joonbug+diagnostics-watch@chromium.org',
                        'michaelcheco+diagnostics-watch@google.com',
                        'zentaro+diagnostics-watch@chromium.org'],