Credential Manager: Add platform-exposed Credential objects.

Source/platform/credentialmanager/PlatformFederatedCredential.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 "platform/credentialmanager/PlatformFederatedCredential.h"
+
+namespace blink {
+
+PlatformFederatedCredential* PlatformFederatedCredential::create(const String& id, const String& name, const String& avatarURL, const String& federation)
+{
+    return new PlatformFederatedCredential(id, name, avatarURL, federation);
+}
+
+PlatformFederatedCredential::PlatformFederatedCredential(const String& id, const String& name, const String& avatarURL, const String& federation)
+    : PlatformCredential(id, name, avatarURL)
+    , m_federation(federation)
+{
+}
+
+PlatformFederatedCredential::~PlatformFederatedCredential()
+{
+}
+
+} // namespace blink