Replace PlaceholderFrameOwner with RemoteBridgeFrameOwner.

Source/web/RemoteBridgeFrameOwner.cpp

+// Copyright 2015 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 "web/RemoteBridgeFrameOwner.h"
+
+namespace blink {
+
+RemoteBridgeFrameOwner::RemoteBridgeFrameOwner(PassRefPtrWillBeRawPtr<WebLocalFrameImpl> frame, SandboxFlags flags)
+    : m_frame(frame)
+    , m_sandboxFlags(flags)
+{
+}
+
+void RemoteBridgeFrameOwner::trace(Visitor* visitor)
+{
+    visitor->trace(m_frame);
+    FrameOwner::trace(visitor);
+}
+
+void RemoteBridgeFrameOwner::dispatchLoad()
+{
+    // FIXME: Implement. Most likely goes through m_frame->client().
+}
+
+} // namespace blink