Run clang-modernize -use-nullptr over src/extensions/.

extensions/common/permissions/manifest_permission_set.cc

Index: extensions/common/permissions/manifest_permission_set.cc
diff --git a/extensions/common/permissions/manifest_permission_set.cc b/extensions/common/permissions/manifest_permission_set.cc
index fecb611dbe16ea7a2ef729b86aceddeebde86f8d..c8450068da4f45cf3374dcc874d5608b2c76376f 100644
--- a/extensions/common/permissions/manifest_permission_set.cc
+++ b/extensions/common/permissions/manifest_permission_set.cc
@@ -64,9 +64,9 @@ bool ManifestPermissionSet::ParseFromJSON(
     std::vector<std::string>* unhandled_permissions) {
   for (size_t i = 0; i < permissions->GetSize(); ++i) {
     std::string permission_name;
-    const base::Value* permission_value = NULL;
+    const base::Value* permission_value = nullptr;
     if (!permissions->GetString(i, &permission_name)) {
-      const base::DictionaryValue* dict = NULL;
+      const base::DictionaryValue* dict = nullptr;
       // permission should be a string or a single key dict.
       if (!permissions->GetDictionary(i, &dict) || dict->size() != 1) {
         if (error) {