Support Sync following Gaia OAuth authentication

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index fd8833d9edc9d16bc414a747bcbc66b87f55f723..9b693577bfdb222fc7cec85eb9a535b28fda6c88 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1276,6 +1276,9 @@ const char kAutofillProfileMigrated[] = "sync.autofill_migrated";
 // startup so that the user doesn't need to provide credentials on each start.
 const char kEncryptionBootstrapToken[] = "sync.encryption_bootstrap_token";
 
+// Boolean tracking whether the user authenticated with OAuth.
+const char kSyncUsingOAuth[] = "sync.using_oauth";
+
 // Boolean tracking whether the user chose to specify a secondary encryption
 // passphrase.
 const char kSyncUsingSecondaryPassphrase[] = "sync.using_secondary_passphrase";