Bug 1521017 - Using NS_NAMED_LITERNAL_CSTRING to avoid increasing the number of static constructors; r=asuth

This patch uses nsLiteralCString instead of nsCString for avoiding increasing
the number of static constructors. Also, it removes the declaration of
kInternalError and kExternalError on Beta and Release since they won't be use
in these channels.

Differential Revision: https://phabricator.services.mozilla.com/D16981

--HG--
extra : moz-landing-system : lando

dom/quota/QuotaCommon.cpp

@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "QuotaCommon.h"
+
+BEGIN_QUOTA_NAMESPACE
+
+#ifdef NIGHTLY_BUILD
+NS_NAMED_LITERAL_CSTRING(kInternalError, "internal");
+NS_NAMED_LITERAL_CSTRING(kExternalError, "external");
+#endif
+
+END_QUOTA_NAMESPACE

dom/quota/QuotaCommon.h

@@ -73,11 +73,12 @@ BEGIN_QUOTA_NAMESPACE
 
 // Telemetry keys to indicate types of errors.
 #ifdef NIGHTLY_BUILD
-const nsCString kInternalError = NS_LITERAL_CSTRING("internal");
-const nsCString kExternalError = NS_LITERAL_CSTRING("external");
+extern const nsLiteralCString kInternalError;
+extern const nsLiteralCString kExternalError;
 #else
-const nsCString kInternalError = EmptyCString();
-const nsCString kExternalError = EmptyCString();
+// No need for these when we're not collecting telemetry.
+#  define kInternalError
+#  define kExternalError
 #endif
 
 class BackgroundThreadObject {

dom/quota/moz.build

@@ -54,6 +54,7 @@ UNIFIED_SOURCES += [
     'ActorsParent.cpp',
     'FileStreams.cpp',
     'MemoryOutputStream.cpp',
+    'QuotaCommon.cpp',
     'QuotaManagerService.cpp',
     'QuotaRequests.cpp',
     'QuotaResults.cpp',