Define watchlist for structured_headers.

Change-Id: Ida8184de82d7ed7c695a89ec7142f08485f002a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2055669
Auto-Submit: Ian Clelland <iclelland@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741441}

WATCHLISTS

@@ -1680,6 +1680,9 @@
     'storage_service' : {
       'filepath': 'components/services/storage/',
     },
+    'structured_headers' : {
+      'filepath': 'net/http/structured_headers*',
+    },
     'styleguide': {
       'filepath': '^styleguide/',
     },
@@ -2680,6 +2683,7 @@
     'startup': ['grt+watch@chromium.org',
                 'pastarmovj+watch@chromium.org'],
     'storage_service': ['dmurph+watching-storageservice@chromium.org'],
+    'structured_headers': ['iclelland+watch@chromium.org'],
     'styleguide': ['danakj+watch@chromium.org',
                    'jbroman+cpp@chromium.org',
                    'vmpstr+watch@chromium.org'],