[Sync::Cleanup] Do not handle NOTREACHED failures in SyncPrefs.

Change-Id: I1a8ef527472d65b5f24b7357fe9ac6b153879d03
Reviewed-on: https://chromium-review.googlesource.com/1124848
Commit-Queue: vitaliii <vitaliii@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572557}

components/sync/base/sync_prefs.cc

@@ -433,20 +433,14 @@ void SyncPrefs::RegisterDataTypePreferredPref(
     ModelType type,
     bool is_preferred) {
   const char* pref_name = GetPrefNameForDataType(type);
-  if (!pref_name) {
-    NOTREACHED();
-    return;
-  }
+  DCHECK(pref_name);
   registry->RegisterBooleanPref(pref_name, is_preferred);
 }
 
 bool SyncPrefs::GetDataTypePreferred(ModelType type) const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   const char* pref_name = GetPrefNameForDataType(type);
-  if (!pref_name) {
-    NOTREACHED();
-    return false;
-  }
+  DCHECK(pref_name);
 
   if (AlwaysPreferredUserTypes().Has(type))
     return true;
@@ -465,10 +459,7 @@ bool SyncPrefs::GetDataTypePreferred(ModelType type) const {
 void SyncPrefs::SetDataTypePreferred(ModelType type, bool is_preferred) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   const char* pref_name = GetPrefNameForDataType(type);
-  if (!pref_name) {
-    NOTREACHED();
-    return;
-  }
+  DCHECK(pref_name);
 
   if (AlwaysPreferredUserTypes().Has(type))
     return;