Delay loading the NTP after sign in until MergeSession has been performed in

chrome/browser/signin/google_auto_login_helper.h

 // Copyright 2013 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.
 
-#ifndef CHROME_BROWSER_ANDROID_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_
-#define CHROME_BROWSER_ANDROID_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_
+#ifndef CHROME_BROWSER_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_
+#define CHROME_BROWSER_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_
 
 #include <deque>
 
+#include "base/observer_list.h"
 #include "chrome/browser/signin/ubertoken_fetcher.h"
 #include "google_apis/gaia/gaia_auth_consumer.h"
 
 class GaiaAuthFetcher;
+class GoogleServiceAuthError;
 class Profile;
 
-// Logs in the current signed in user into Google services. Populates the cookie
-// jar with Google credentials of the signed in user.
+// Merges a Google account known to Chrome into the cookie jar.  Once the
+// account is merged, successfully or not, a NOTIFICATION_MERGE_SESSION_COMPLETE
+// notification is sent out.  When merging multiple accounts, one instance of
+// the helper is better than multiple instances if there is the possibility
+// that they run concurrently, since changes to the cookie must be serialized.
+//
+// By default instances of GoogleAutoLoginHelper delete themselves when done.
 class GoogleAutoLoginHelper : public GaiaAuthConsumer,

[guohui, 2013/12/20 16:11:09]

The class has changed a lot to the point that its name does not seem to make
sense any more. Maybe change it to MergeSessionHelper?

                               public UbertokenConsumer {
  public:
-  explicit GoogleAutoLoginHelper(Profile* profile);
+  class Observer {
+   public:
+    // Called whenever a merge session is completed.  The account that was
+    // merged is given by |account_id|.  If |error| is equal to
+    // GoogleServiceAuthError::AuthErrorNone() then the merge succeeeded.
+    virtual void MergeSessionCompleted(const std::string& account_id,
+                                       const GoogleServiceAuthError& error) = 0;
+   protected:
+    virtual ~Observer() {}
+  };
+
+  GoogleAutoLoginHelper(Profile* profile, Observer* observer);
   virtual ~GoogleAutoLoginHelper();
 
   void LogIn();
   void LogIn(const std::string& account_id);
 
+  // Add or remove observers of this helper.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ protected:
+  Profile* profile() { return profile_; }
+
+  // Overridden from UbertokenConsumer.
+  virtual void OnUbertokenSuccess(const std::string& token) OVERRIDE;
+  virtual void OnUbertokenFailure(const GoogleServiceAuthError& error) OVERRIDE;
+
   // Overridden from GaiaAuthConsumer.
   virtual void OnMergeSessionSuccess(const std::string& data) OVERRIDE;
   virtual void OnMergeSessionFailure(const GoogleServiceAuthError& error)
       OVERRIDE;
 
-  // Overridden from UbertokenConsumer.
-  virtual void OnUbertokenSuccess(const std::string& token) OVERRIDE;
-  virtual void OnUbertokenFailure(const GoogleServiceAuthError& error) OVERRIDE;
+ private:
+  // Starts the proess of fetching the uber token and performing a merge session
+  // for the next account.  Virtual so that it can be overriden in tests.
+  virtual void StartFetching();
 
-  // For testing.
-  virtual UbertokenFetcher* CreateNewUbertokenFetcher();
-  virtual GaiaAuthFetcher* CreateNewGaiaAuthFetcher();
+  // Call observer when merge session completes.
+  void SignalComplete(const std::string& account_id,
+                      const GoogleServiceAuthError& error);
 
- private:
+  // Start the next merge session, if needed.
+  void MergeNextAccount();
+
   Profile* profile_;
   scoped_ptr<GaiaAuthFetcher> gaia_auth_fetcher_;
   scoped_ptr<UbertokenFetcher> uber_token_fetcher_;
   std::deque<std::string> accounts_;
 
+  // List of observers to notify when merge session completes.
+  // Makes sure list is empty on destruction.
+  ObserverList<Observer, true> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(GoogleAutoLoginHelper);
 };
 
-#endif  // CHROME_BROWSER_ANDROID_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_
+#endif  // CHROME_BROWSER_SIGNIN_GOOGLE_AUTO_LOGIN_HELPER_H_