[PresentationAPI] Implementing start/joinSession from WebPresentationClient to PresentationService.

content/renderer/presentation/presentation_session_dispatcher.cc

+// 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 "content/renderer/presentation/presentation_session_dispatcher.h"
+
+#include "base/logging.h"
+
+namespace content {
+
+PresentationSessionDispatcher::PresentationSessionDispatcher(
+    mojo::InterfaceRequest<presentation::PresentationSession> session_request,
+    const std::string& url,
+    const std::string& id)
+    : session_binding_(this, session_request.Pass()),
+      url_(url),
+      id_(id) {
+}
+
+PresentationSessionDispatcher::~PresentationSessionDispatcher() {
+}
+
+blink::WebString PresentationSessionDispatcher::getUrl() {
+  return blink::WebString::fromUTF8(url_);
+}
+
+blink::WebString PresentationSessionDispatcher::getId() {
+  return blink::WebString::fromLatin1(id_);
+}
+
+}  // namespace content