Refactor AO2TS to make it easier to componentize.

components/signin/core/browser/account_tracker_service_unittest.cc

Index: components/signin/core/browser/account_tracker_service_unittest.cc
diff --git a/components/signin/core/browser/account_tracker_service_unittest.cc b/components/signin/core/browser/account_tracker_service_unittest.cc
index 626b1028b707861192dfe3c1ef11f00cf16a2442..8c83d0bbe43bdf3a5f39fdcac7b52caa1f05567e 100644
--- a/components/signin/core/browser/account_tracker_service_unittest.cc
+++ b/components/signin/core/browser/account_tracker_service_unittest.cc
@@ -274,11 +274,12 @@ class AccountTrackerServiceTest : public testing::Test {
   }
 
   void SimulateTokenAvailable(const std::string& account_id) {
-    fake_oauth2_token_service_->AddAccount(account_id);
+    fake_oauth2_token_service_->GetDelegate()->UpdateCredentials(
+        account_id, "refresh_token");
   }
 
   void SimulateTokenRevoked(const std::string& account_id) {
-    fake_oauth2_token_service_->RemoveAccount(account_id);
+    fake_oauth2_token_service_->GetDelegate()->RevokeCredentials(account_id);
   }
 
   // Helpers to fake access token and user info fetching