Revert of Revert of Elimate NOTIFICATION_GOOGLE_URL_UPDATED

chrome/browser/google/google_url_tracker.h

 // Copyright (c) 2012 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_GOOGLE_GOOGLE_URL_TRACKER_H_
 #define CHROME_BROWSER_GOOGLE_GOOGLE_URL_TRACKER_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 21 matching lines @@
 namespace infobars {
 class InfoBar;
 }
 
 // This object is responsible for checking the Google URL once per network
 // change, and if necessary prompting the user to see if they want to change to
 // using it.  The current and last prompted values are saved to prefs.
 //
 // Most consumers should only call GoogleURL(), which is guaranteed to
 // synchronously return a value at all times (even during startup or in unittest
-// mode).  Consumers who need to be notified when things change should listen to
-// the notification service for NOTIFICATION_GOOGLE_URL_UPDATED, which provides
-// the original and updated values.
+// mode).  Consumers who need to be notified when things change should register
+// a callback that provides the original and updated values via
+// RegisterCallback().
 //
 // To protect users' privacy and reduce server load, no updates will be
 // performed (ever) unless at least one consumer registers interest by calling
 // RequestServerCheck().
 class GoogleURLTracker : public net::URLFetcherDelegate,
                          public net::NetworkChangeNotifier::IPAddressObserver,
                          public KeyedService {
  public:
   // Callback that is called when the Google URL is updated. The arguments are
   // the old and new URLs.
   typedef base::Callback<void(GURL, GURL)> OnGoogleURLUpdatedCallback;
   typedef base::CallbackList<void(GURL, GURL)> CallbackList;
   typedef CallbackList::Subscription Subscription;
 
-  // The contents of the Details for a NOTIFICATION_GOOGLE_URL_UPDATED.
-  typedef std::pair<GURL, GURL> UpdatedDetails;
-
   // The constructor does different things depending on which of these values
   // you pass it.  Hopefully these are self-explanatory.
   enum Mode {
     NORMAL_MODE,
     UNIT_TEST_MODE,
   };
 
   static const char kDefaultGoogleHomepage[];
   static const char kSearchDomainCheckURL[];
 
@@ skipping 132 matching lines @@
   GURL fetched_google_url_;
   scoped_ptr<net::URLFetcher> fetcher_;
   int fetcher_id_;
   bool in_startup_sleep_;  // True if we're in the five-second "no fetching"
                            // period that begins at browser start.
   bool already_fetched_;   // True if we've already fetched a URL once this run;
                            // we won't fetch again until after a restart.
   bool need_to_fetch_;     // True if a consumer actually wants us to fetch an
                            // updated URL.  If this is never set, we won't
                            // bother to fetch anything.
-                           // Consumers should observe
-                           // chrome::NOTIFICATION_GOOGLE_URL_UPDATED.
+                           // Consumers should register a callback via
+                           // RegisterCallback().
   bool need_to_prompt_;    // True if the last fetched Google URL is not
                            // matched with current user's default Google URL
                            // nor the last prompted Google URL.
   bool search_committed_;  // True when we're expecting a notification of a new
                            // pending search navigation.
   EntryMap entry_map_;
   base::WeakPtrFactory<GoogleURLTracker> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GoogleURLTracker);
 };
 
 #endif  // CHROME_BROWSER_GOOGLE_GOOGLE_URL_TRACKER_H_