Add Statistics for SupervisedUserSettingService during merging and syncing data.

chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.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 "chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.h"
 
 #include <map>
 #include <set>
 #include <utility>
 
@@ skipping 214 matching lines @@
     callbacks_.Notify(su_id, key);
 
     seen_keys[su_id].insert(key);
   }
 
   // Iterate over all settings that we have locally, which includes settings
   // that were just synced down. We filter those out using |seen_keys|.
   SyncChangeList change_list;
   const DictionaryValue* all_settings =
       prefs_->GetDictionary(prefs::kSupervisedUserSharedSettings);
+  int num_association = 0;
   for (DictionaryValue::Iterator it(*all_settings); !it.IsAtEnd();
        it.Advance()) {
     const DictionaryValue* dict = NULL;
     bool success = it.value().GetAsDictionary(&dict);
     DCHECK(success);
 
+    num_association += dict->size();
     const std::set<std::string>& seen = seen_keys[it.key()];
     for (DictionaryValue::Iterator jt(*dict); !jt.IsAtEnd(); jt.Advance()) {
       // We only need to upload settings that we haven't seen in the initial
       // sync data (which means they were added locally).
       if (seen.count(jt.key()) > 0)
         continue;
 
       SyncData data = CreateSyncDataForValue(it.key(), jt.key(), jt.value());
       DCHECK(data.IsValid());
       change_list.push_back(
           SyncChange(FROM_HERE, SyncChange::ACTION_ADD, data));
     }
   }
 
   SyncMergeResult result(SUPERVISED_USER_SHARED_SETTINGS);
   // Process all the accumulated changes.
   if (change_list.size() > 0) {
     result.set_error(
         sync_processor_->ProcessSyncChanges(FROM_HERE, change_list));
   }
 
-  // TODO(bauerb): Statistics?
+  result.set_num_items_added(change_list.size());

[Bernhard Bauer, 2016/01/05 09:37:30]

Wait, is this right? IIUC, num_items_added is the number of items added to the
_local_ set of data, whereas this is the number of items added remotely.

[Deepak, 2016/01/05 13:29:19]

Done.

+  result.set_num_items_before_association(num_association - change_list.size());
+  result.set_num_items_after_association(num_association);
   return result;
 }
 
 void SupervisedUserSharedSettingsService::StopSyncing(syncer::ModelType type) {
   DCHECK_EQ(SUPERVISED_USER_SHARED_SETTINGS, type);
   sync_processor_.reset();
   error_handler_.reset();
 }
 
 syncer::SyncDataList SupervisedUserSharedSettingsService::GetAllSyncData(
@@ skipping 64 matching lines @@
         NOTREACHED();
         break;
       }
     }
     callbacks_.Notify(su_id, key);
   }
 
   SyncError error;
   return error;
 }