Use stricter type checking in UMA_HISTOGRAM_ENUMERATION

components/sync/driver/async_directory_type_controller.cc

Index: components/sync/driver/async_directory_type_controller.cc
diff --git a/components/sync/driver/async_directory_type_controller.cc b/components/sync/driver/async_directory_type_controller.cc
index a821b212f5d98779bc6b7af45e2e2c1af10f149b..51576a6b1afe9f942e852b5f068e47cf7f910f84 100644
--- a/components/sync/driver/async_directory_type_controller.cc
+++ b/components/sync/driver/async_directory_type_controller.cc
@@ -207,8 +207,10 @@ void AsyncDirectoryTypeController::StartDone(
 
 void AsyncDirectoryTypeController::RecordStartFailure(ConfigureResult result) {
   DCHECK(CalledOnValidThread());
+  // TODO(wychen): enum uma should be strongly typed. crbug.com/661401
   UMA_HISTOGRAM_ENUMERATION("Sync.DataTypeStartFailures",
-                            ModelTypeToHistogramInt(type()), MODEL_TYPE_COUNT);
+                            ModelTypeToHistogramInt(type()),
+                            static_cast<int>(MODEL_TYPE_COUNT));
 #define PER_DATA_TYPE_MACRO(type_str)                                    \
   UMA_HISTOGRAM_ENUMERATION("Sync." type_str "ConfigureFailure", result, \
                             MAX_CONFIGURE_RESULT);