Use stricter type checking in UMA_HISTOGRAM_ENUMERATION

ios/chrome/browser/ui/sync/sync_util.mm

 // Copyright 2012 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.
 
 #import "ios/chrome/browser/ui/sync/sync_util.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "components/infobars/core/infobar_manager.h"
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/browser/browser_state/chrome_browser_state.h"
@@ skipping 10 matching lines @@
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 // Enumerated constants for logging when a sign-in error infobar was shown
 // to the user. This was added for crbug/265352 to quantify how often this
 // bug shows up in the wild. The logged histogram count should be interpreted
 // as a ratio of the number of active sync users.
-enum {
+enum ErrorState {
   SYNC_SIGN_IN_NEEDS_UPDATE = 1,
   SYNC_SERVICE_UNAVAILABLE,
   SYNC_NEEDS_PASSPHRASE,
   SYNC_UNRECOVERABLE_ERROR,
   SYNC_ERROR_COUNT
 };
 
 }  // namespace
 
 namespace ios_internal {
@@ skipping 93 matching lines @@
   SyncSetupService* syncSetupService =
       SyncSetupServiceFactory::GetForBrowserState(browser_state);
   if (!syncSetupService)
     return false;
   SyncSetupService::SyncServiceState errorState =
       syncSetupService->GetSyncServiceState();
   if (IsTransientSyncError(errorState))
     return false;
 
   // Logs when an infobar is shown to user. See crbug/265352.
-  int loggedErrorState = 0;
+  ErrorState loggedErrorState = SYNC_ERROR_COUNT;
   switch (errorState) {
     case SyncSetupService::kNoSyncServiceError:
     case SyncSetupService::kSyncServiceCouldNotConnect:
     case SyncSetupService::kSyncServiceServiceUnavailable:
       NOTREACHED();
       break;
     case SyncSetupService::kSyncServiceSignInNeedsUpdate:
       loggedErrorState = SYNC_SIGN_IN_NEEDS_UPDATE;
       break;
     case SyncSetupService::kSyncServiceNeedsPassphrase:
@@ skipping 19 matching lines @@
       return true;
     case SyncSetupService::kSyncServiceSignInNeedsUpdate:
     case SyncSetupService::kSyncServiceNeedsPassphrase:
     case SyncSetupService::kSyncServiceUnrecoverableError:
       return false;
   }
 }
 
 }  // namespace sync
 }  // namespace ios_internal