Credential manager: Convert strings to URLs early.

Source/platform/credentialmanager/PlatformFederatedCredential.h

 // 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.
 
 #ifndef PlatformFederatedCredential_h
 #define PlatformFederatedCredential_h
 
 #include "platform/credentialmanager/PlatformCredential.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class PLATFORM_EXPORT PlatformFederatedCredential FINAL : public PlatformCredential {
     WTF_MAKE_NONCOPYABLE(PlatformFederatedCredential);
 public:
-    static PlatformFederatedCredential* create(const String& id, const String& name, const String& avatarURL, const String& federation);
+    static PlatformFederatedCredential* create(const String& id, const String& name, const KURL& avatarURL, const KURL& federation);
     virtual ~PlatformFederatedCredential();
 
-    const String& federation() const { return m_federation; }
+    const KURL& federation() const { return m_federation; }
 
 private:
-    PlatformFederatedCredential(const String& id, const String& name, const String& avatarURL, const String& federation);
+    PlatformFederatedCredential(const String& id, const String& name, const KURL& avatarURL, const KURL& federation);
 
-    String m_federation;
+    KURL m_federation;
 };
 
 } // namespace blink
 
 #endif // PlatformFederatedCredential_h