Add blundell as OWNER of //google_apis/gaia for O2TS refactor reviewing

Bug: 950159
Change-Id: I587995f70d0f4cad06fde64ce91612fbe57b854a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1658009
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669149}

google_apis/gaia/OWNERS

@@ -2,4 +2,8 @@ droger@chromium.org
 msarda@chromium.org
 rogerta@chromium.org
 
+# Solely for the duration of the refactoring of OAuth2TokenService
+# (https://crbug.com/950159). Do not choose for any other reviews.
+blundell@chromium.org
+
 # COMPONENT: Services>SignIn