[Sync] Deprecate old histograms

components/sync_driver/device_info_sync_service.cc

Index: components/sync_driver/device_info_sync_service.cc
diff --git a/components/sync_driver/device_info_sync_service.cc b/components/sync_driver/device_info_sync_service.cc
index 879d4d824805774c92898e3eb8cbfcf4886662d4..22b8d8fa7ba275c9908cee1d8f8b272d9aaf12f5 100644
--- a/components/sync_driver/device_info_sync_service.cc
+++ b/components/sync_driver/device_info_sync_service.cc
@@ -10,7 +10,6 @@
 #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"
@@ -31,38 +30,6 @@ 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) {
@@ -114,15 +81,6 @@ SyncMergeResult DeviceInfoSyncService::MergeDataAndStartSyncing(
       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