Add ios/c/b/passwords to WATCHLISTS

The WATCHLISTS have a group for password manager, but it lacks the ios part.
This CL adds that part.

BUG=None
R=vasilii@chromium.org

Review-Url: https://codereview.chromium.org/2031513003
Cr-Commit-Position: refs/heads/master@{#397141}

WATCHLISTS

@@ -667,6 +667,7 @@
                   '|chrome/test/data/password'\
                   '|components/autofill.*password'
                   '|components/password_'\
+                  '|^ios/chrome/browser/passwords'\
     },
     'pepper_api': {
       'filepath': 'ppapi/api'\