Cleanup: Pass std::string as const reference if possible

google_apis/gaia/account_tracker_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "google_apis/gaia/account_tracker.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/message_loop/message_loop.h"
@@ skipping 11 matching lines @@
 
 const char kPrimaryAccountKey[] = "primary_account@example.com";
 
 enum TrackingEventType {
   ADDED,
   REMOVED,
   SIGN_IN,
   SIGN_OUT
 };
 
-std::string AccountKeyToObfuscatedId(const std::string email) {
+std::string AccountKeyToObfuscatedId(const std::string& email) {
   return "obfid-" + email;
 }
 
 class TrackingEvent {
  public:
   TrackingEvent(TrackingEventType type,
                 const std::string& account_key,
                 const std::string& gaia_id)
       : type_(type),
         account_key_(account_key),
@@ skipping 244 matching lines @@
   AccountTrackerObserver* observer() {
     return &observer_;
   }
 
   AccountTracker* account_tracker() {
     return account_tracker_.get();
   }
 
   // Helpers to pass fake events to the tracker.
 
-  void NotifyLogin(const std::string account_key) {
+  void NotifyLogin(const std::string& account_key) {
     identity_provider()->LogIn(account_key);
   }
 
   void NotifyLogout() { identity_provider()->LogOut(); }
 
   void NotifyTokenAvailable(const std::string& username) {
     fake_oauth2_token_service_->AddAccount(username);
   }
 
   void NotifyTokenRevoked(const std::string& username) {
     fake_oauth2_token_service_->RemoveAccount(username);
   }
 
   // Helpers to fake access token and user info fetching
   void IssueAccessToken(const std::string& username) {
     fake_oauth2_token_service_->IssueAllTokensForAccount(
         username, "access_token-" + username, base::Time::Max());
   }
 
-  std::string GetValidTokenInfoResponse(const std::string account_key) {
+  std::string GetValidTokenInfoResponse(const std::string& account_key) {
     return std::string("{ \"id\": \"") + AccountKeyToObfuscatedId(account_key) +
            "\" }";
   }
 
   void ReturnOAuthUrlFetchResults(int fetcher_id,
                                   net::HttpStatusCode response_code,
                                   const std::string& response_string);
 
   void ReturnOAuthUrlFetchSuccess(const std::string& account_key);
   void ReturnOAuthUrlFetchFailure(const std::string& account_key);
@@ skipping 478 matching lines @@
   EXPECT_TRUE(ids.email.empty());
   EXPECT_TRUE(ids.gaia.empty());
 
   ids = account_tracker()->FindAccountIdsByGaiaId("alpha@example.com");
   EXPECT_TRUE(ids.account_key.empty());
   EXPECT_TRUE(ids.email.empty());
   EXPECT_TRUE(ids.gaia.empty());
 }
 
 }  // namespace gaia