[Sync] Deprecate old histograms

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 <stddef.h>
 
 #include <algorithm>
 #include <utility>
 
 #include "base/memory/ptr_util.h"
-#include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "components/sync_driver/device_info_util.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 base::Time;
 using base::TimeDelta;
 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
-// (crbug/481596).
-// 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_info_provider_(local_device_info_provider) {
   DCHECK(local_device_info_provider);
 }
 
 DeviceInfoSyncService::~DeviceInfoSyncService() {
 }
 
 SyncMergeResult DeviceInfoSyncService::MergeDataAndStartSyncing(
@@ skipping 31 matching lines @@
        ++iter) {
     DCHECK_EQ(syncer::DEVICE_INFO, iter->GetDataType());
 
     const std::string& id = iter->GetSpecifics().device_info().cache_guid();
 
     if (id == local_device_info->guid()) {
       // |initial_sync_data| contains data matching the local device.
       std::unique_ptr<DeviceInfo> synced_local_device_info =
           base::WrapUnique(CreateDeviceInfo(*iter));
 
-      // TODO(pavely): Remove histogram once device_id mismatch is understood
-      // (crbug/481596).
-      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());
-      }
-
       pulse_delay = DeviceInfoUtil::CalculatePulseDelay(
           GetLastUpdateTime(*iter), Time::Now());
       // Store the synced device info for the local device only if
       // 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) &&
           !pulse_delay.is_zero()) {
         change_type = SyncChange::ACTION_INVALID;
       } else {
@@ skipping 239 matching lines @@
     return syncer::SyncDataRemote(device_info).GetModifiedTime();
   } else {
     // We shouldn't reach this point for remote data, so this means we're likely
     // looking at the local device info. Using a long ago time is perfect, since
     // the desired behavior is to update/pulse our data as soon as possible.
     return Time();
   }
 }
 
 }  // namespace sync_driver