Credential manager: Convert strings to URLs early.

Source/platform/exported/WebLocalCredential.cpp

 // 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 "config.h"
 #include "public/platform/WebLocalCredential.h"
 
 #include "platform/credentialmanager/PlatformLocalCredential.h"
 
 namespace blink {
 
-WebLocalCredential::WebLocalCredential(const WebString& id, const WebString& name, const WebString& avatarURL, const WebString& password)
+WebLocalCredential::WebLocalCredential(const WebString& id, const WebString& name, const WebURL& avatarURL, const WebString& password)
     : WebCredential(PlatformLocalCredential::create(id, name, avatarURL, password))
 {
 }
 
 void WebLocalCredential::assign(const WebLocalCredential& other)
 {
     m_platformCredential = other.m_platformCredential;
 }
 
 WebString WebLocalCredential::password() const
 {
     return static_cast<PlatformLocalCredential*>(m_platformCredential.get())->password();
 }
 
 } // namespace blink