[Sync] Deprecate old histograms

components/sync_driver/glue/sync_backend_host_core.cc

Index: components/sync_driver/glue/sync_backend_host_core.cc
diff --git a/components/sync_driver/glue/sync_backend_host_core.cc b/components/sync_driver/glue/sync_backend_host_core.cc
index 0871e277269ef706014d1948304d80c36e3141b2..a36b4b768ffad00aa80d557db9654158884cf60d 100644
--- a/components/sync_driver/glue/sync_backend_host_core.cc
+++ b/components/sync_driver/glue/sync_backend_host_core.cc
@@ -9,7 +9,6 @@
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
-#include "base/metrics/histogram.h"
 #include "base/single_thread_task_runner.h"
 #include "components/data_use_measurement/core/data_use_user_data.h"
 #include "components/invalidation/public/invalidation_util.h"
@@ -47,15 +46,6 @@ class URLFetcher;
 
 namespace {
 
-// Enums for UMAs.
-enum SyncBackendInitState {
-    SETUP_COMPLETED_FOUND_RESTORED_TYPES = 0,
-    SETUP_COMPLETED_NO_RESTORED_TYPES,
-    FIRST_SETUP_NO_RESTORED_TYPES,
-    FIRST_SETUP_RESTORED_TYPES,
-    SYNC_BACKEND_INIT_STATE_COUNT
-};
-
 void BindFetcherToDataTracker(net::URLFetcher* fetcher) {
   data_use_measurement::DataUseUserData::AttachToFetcher(
       fetcher, data_use_measurement::DataUseUserData::SYNC);
@@ -188,22 +178,6 @@ void SyncBackendHostCore::OnInitializationComplete(
   js_backend_ = js_backend;
   debug_info_listener_ = debug_info_listener;
 
-  // Track whether or not sync DB and preferences were in sync.
-  SyncBackendInitState backend_init_state;
-  if (has_sync_setup_completed_ && !restored_types.Empty()) {
-    backend_init_state = SETUP_COMPLETED_FOUND_RESTORED_TYPES;
-  } else if (has_sync_setup_completed_ && restored_types.Empty()) {
-    backend_init_state = SETUP_COMPLETED_NO_RESTORED_TYPES;
-  } else if (!has_sync_setup_completed_ && restored_types.Empty()) {
-    backend_init_state = FIRST_SETUP_NO_RESTORED_TYPES;
-  } else {  // (!has_sync_setup_completed_ && !restored_types.Empty())
-    backend_init_state = FIRST_SETUP_RESTORED_TYPES;
-  }
-
-  UMA_HISTOGRAM_ENUMERATION("Sync.BackendInitializeRestoreState",
-                            backend_init_state,
-                            SYNC_BACKEND_INIT_STATE_COUNT);
-
   // Before proceeding any further, we need to download the control types and
   // purge any partial data (ie. data downloaded for a type that was on its way
   // to being initially synced, but didn't quite make it.).  The following