[Extensions Bindings] Fix uninitialized member in ArgumentSpec

extensions/renderer/argument_spec.cc

 // Copyright 2016 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 "extensions/renderer/argument_spec.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_piece.h"
 #include "base/values.h"
 #include "content/public/child/v8_value_converter.h"
@@ skipping 54 matching lines @@
   }
   if (maximum && value > *maximum) {
     *error = api_errors::NumberTooLarge(*maximum);
     return false;
   }
   return true;
 }
 
 }  // namespace
 
-ArgumentSpec::ArgumentSpec(const base::Value& value)
-    : type_(ArgumentType::INTEGER), optional_(false), preserve_null_(false) {
+ArgumentSpec::ArgumentSpec(const base::Value& value) {
   const base::DictionaryValue* dict = nullptr;
   CHECK(value.GetAsDictionary(&dict));
   dict->GetBoolean("optional", &optional_);
   dict->GetString("name", &name_);
 
   InitializeType(dict);
 }
 
-ArgumentSpec::ArgumentSpec(ArgumentType type) : type_(type), optional_(false) {}
+ArgumentSpec::ArgumentSpec(ArgumentType type) : type_(type) {}
 
 void ArgumentSpec::InitializeType(const base::DictionaryValue* dict) {
   std::string ref_string;
   if (dict->GetString("$ref", &ref_string)) {
     ref_ = std::move(ref_string);
     type_ = ArgumentType::REF;
     return;
   }
 
   {
@@ skipping 522 matching lines @@
       break;
     case ArgumentType::CHOICES:
     case ArgumentType::ANY:
       NOTREACHED();
   }
 
   return api_errors::InvalidType(expected_type, GetV8ValueTypeString(value));
 }
 
 }  // namespace extensions