Use my chromium.org account in OWNER and WATCHLIST files.

Note: My google.com account had commit access earlier; but now I have
commit access for chromium.org account.

BUG=

Review URL: https://codereview.chromium.org/854933002

Cr-Commit-Position: refs/heads/master@{#311786}

WATCHLISTS

@@ -910,7 +910,7 @@
                 'kmadhusu+watch@chromium.org', 'dhollowa+watch@chromium.org',
                 'jfweitz+watch@chromium.org', 'skanuj+watch@chromium.org'],
     'ipc': ['jam@chromium.org', 'darin-cc@chromium.org'],
-    'libwebp': ['urvang@google.com', 'jzern@chromium.org',
+    'libwebp': ['urvang@chromium.org', 'jzern@chromium.org',
                 'skal@google.com', 'vikasa@google.com'],
     'linux_fonts': ['derat+watch@chromium.org'],
     'linux_sandboxing': ['jln+watch@chromium.org'],

third_party/libwebp/OWNERS

 fbarchard@chromium.org
-urvang@google.com
+urvang@chromium.org