[Sync] Record histogram for mismatched device_ids

components/sync_driver/device_info_sync_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 "components/sync_driver/device_info_sync_service.h"
 
+#include "base/metrics/histogram.h"
 #include "base/strings/stringprintf.h"
 #include "components/sync_driver/local_device_info_provider.h"
 #include "sync/api/sync_change.h"
 #include "sync/protocol/sync.pb.h"
 #include "sync/util/time.h"
 
 namespace sync_driver {
 
 using syncer::ModelType;
 using syncer::SyncChange;
 using syncer::SyncChangeList;
 using syncer::SyncChangeProcessor;
 using syncer::SyncData;
 using syncer::SyncDataList;
 using syncer::SyncErrorFactory;
 using syncer::SyncMergeResult;
 
+namespace {
+
+// TODO(pavely): Remove histogram once device_id mismatch is understood.

[stanisc, 2015/04/24 23:05:40]

Perhaps mention the crbug here.

[pavely, 2015/04/27 18:40:35]

Done.

+// When signin_scoped_device_id from pref doesn't match the one in
+// DeviceInfoSpecfics record histogram telling if sync or pref copy was empty.
+// This will indicate how often such mismatch happens and what was the state
+// before.
+enum DeviceIdMismatchForHistogram {
+  DEVICE_ID_MISMATCH_BOTH_NONEMPTY = 0,
+  DEVICE_ID_MISMATCH_SYNC_EMPTY,
+  DEVICE_ID_MISMATCH_PREF_EMPTY,
+  DEVICE_ID_MISMATCH_COUNT,
+};
+
+void RecordDeviceIdChangedHistogram(const std::string& device_id_from_sync,
+                                    const std::string& device_id_from_pref) {
+  DCHECK(device_id_from_sync != device_id_from_pref);
+  DeviceIdMismatchForHistogram device_id_mismatch_for_histogram =
+      DEVICE_ID_MISMATCH_BOTH_NONEMPTY;
+  if (device_id_from_sync.empty()) {
+    device_id_mismatch_for_histogram = DEVICE_ID_MISMATCH_SYNC_EMPTY;
+  } else if (device_id_from_pref.empty()) {
+    device_id_mismatch_for_histogram = DEVICE_ID_MISMATCH_PREF_EMPTY;
+  }
+  UMA_HISTOGRAM_ENUMERATION("Sync.DeviceIdMismatchDetails",
+                            device_id_mismatch_for_histogram,
+                            DEVICE_ID_MISMATCH_COUNT);
+}
+
+}  // namespace
+
 DeviceInfoSyncService::DeviceInfoSyncService(
     LocalDeviceInfoProvider* local_device_info_provider)
     : local_device_backup_time_(-1),
       local_device_info_provider_(local_device_info_provider) {
   DCHECK(local_device_info_provider);
 }
 
 DeviceInfoSyncService::~DeviceInfoSyncService() {
 }
 
@@ skipping 44 matching lines @@
       int64 synced_backup_time =
           has_synced_backup_time
               ? iter->GetSpecifics().device_info().backup_timestamp()
               : -1;
 
       // Overwrite |local_device_backup_time_| with this value if it
       // hasn't been set yet.
       if (!has_local_device_backup_time() && has_synced_backup_time) {
         set_local_device_backup_time(synced_backup_time);
       }
+      // TODO(pavely): Remove histogram once device_id mismatch is understood.
+      if (synced_local_device_info->signin_scoped_device_id() !=
+          local_device_info->signin_scoped_device_id()) {
+        RecordDeviceIdChangedHistogram(
+            synced_local_device_info->signin_scoped_device_id(),
+            local_device_info->signin_scoped_device_id());
+      }
 
       // Store the synced device info for the local device only
       // it is the same as the local info. Otherwise store the local
       // device info and issue a change further below after finishing
       // processing the |initial_sync_data|.
       if (synced_local_device_info->Equals(*local_device_info) &&
           synced_backup_time == local_device_backup_time()) {
         change_type = SyncChange::ACTION_INVALID;
       } else {
         num_items_updated++;
@@ skipping 246 matching lines @@
   SyncDataMap::iterator iter = all_data_.find(client_id);
   if (iter != all_data_.end()) {
     DVLOG(1) << "Deleting DEVICE_INFO for "
              << iter->second.GetSpecifics().device_info().client_name()
              << " with ID " << client_id;
     all_data_.erase(iter);
   }
 }
 
 }  // namespace sync_driver