Improve GCM enum switch type safety

google_apis/gcm/engine/checkin_request.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 "google_apis/gcm/engine/checkin_request.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 40 matching lines @@
     case HTTP_BAD_REQUEST:
       return "HTTP_BAD_REQUEST";
     case HTTP_UNAUTHORIZED:
       return "HTTP_UNAUTHORIZED";
     case HTTP_NOT_OK:
       return "HTTP_NOT_OK";
     case RESPONSE_PARSING_FAILED:
       return "RESPONSE_PARSING_FAILED";
     case ZERO_ID_OR_TOKEN:
       return "ZERO_ID_OR_TOKEN";
-    default:
+    case STATUS_COUNT:
       NOTREACHED();
-      return "UNKNOWN_STATUS";
+      break;
   }
+  return "UNKNOWN_STATUS";
 }
 
 // Records checkin status to both stats recorder and reports to UMA.
 void RecordCheckinStatusAndReportUMA(CheckinRequestStatus status,
                                      GCMStatsRecorder* recorder,
                                      bool will_retry) {
   UMA_HISTOGRAM_ENUMERATION("GCM.CheckinRequestStatus", status, STATUS_COUNT);
   if (status == SUCCESS)
     recorder->RecordCheckinSuccess();
   else {
@@ skipping 146 matching lines @@
 
   RecordCheckinStatusAndReportUMA(SUCCESS, recorder_, false);
   UMA_HISTOGRAM_COUNTS("GCM.CheckinRetryCount",
                        backoff_entry_.failure_count());
   UMA_HISTOGRAM_TIMES("GCM.CheckinCompleteTime",
                       base::TimeTicks::Now() - request_start_time_);
   callback_.Run(response_proto);
 }
 
 }  // namespace gcm