Add histograms to track synced pref changes.

chrome/browser/prefs/pref_model_associator.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_PREFS_PREF_MODEL_ASSOCIATOR_H_
 #define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/containers/hash_tables.h"
+#include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
+#include "chrome/browser/prefs/synced_pref_observer.h"
 #include "sync/api/sync_data.h"
 #include "sync/api/syncable_service.h"
 
 class PrefRegistrySyncable;
 class PrefServiceSyncable;
 
 namespace sync_pb {
 class PreferenceSpecifics;
 }
 
@@ skipping 65 matching lines @@
 
   // Extract preference value and name from sync specifics.
   base::Value* ReadPreferenceSpecifics(
       const sync_pb::PreferenceSpecifics& specifics,
       std::string* name);
 
   // Returns true if the pref under the given name is pulled down from sync.
   // Note this does not refer to SYNCABLE_PREF.
   bool IsPrefSynced(const std::string& name) const;
 
+  // Adds a SyncedPrefObserver to watch for changes to a specific pref.
+  void AddSyncedPrefObserver(const std::string& name,
+                             SyncedPrefObserver* observer);
+
+  // Removes a SyncedPrefObserver from a pref's list of observers.
+  void RemoveSyncedPrefObserver(const std::string& name,
+                                SyncedPrefObserver* observer);
+
  protected:
   friend class ProfileSyncServicePreferenceTest;
 
   typedef std::map<std::string, syncer::SyncData> SyncDataMap;
 
   // Create an association for a given preference. If |sync_pref| is valid,
   // signifying that sync has data for this preference, we reconcile their data
   // with ours and append a new UPDATE SyncChange to |sync_changes|. If
   // sync_pref is not set, we append an ADD SyncChange to |sync_changes| with
   // the current preference data.
@@ skipping 40 matching lines @@
   // Sync's syncer::SyncChange handler. We push all our changes through this.
   scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
 
   // Sync's error handler. We use this to create sync errors.
   scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
 
   // The datatype that this associator is responible for, either PREFERENCES or
   // PRIORITY_PREFERENCES.
   syncer::ModelType type_;
 
+ private:
+  // Map prefs to lists of observers. Observers will receive notification when
+  // a pref changes, including the detail of whether or not the change came
+  // from sync.
+  typedef ObserverList<SyncedPrefObserver> SyncedPrefObserverList;
+  typedef base::hash_map<std::string, SyncedPrefObserverList*>
+      SyncedPrefObserverMap;
+
+  void NotifySyncedPrefObservers(const std::string& path, bool from_sync) const;
+
+  SyncedPrefObserverMap synced_pref_observers_;
+
   DISALLOW_COPY_AND_ASSIGN(PrefModelAssociator);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_