[Presentation API / Media Router] Clean up default pres URL logic.

chrome/browser/media/router/presentation_request.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 "chrome/browser/media/router/presentation_request.h"
+
+#include "chrome/browser/media/router/media_source_helper.h"
+
+namespace media_router {
+
+PresentationRequest::PresentationRequest(
+    const RenderFrameHostId& render_frame_host_id,
+    const std::string& presentation_url,
+    const GURL& frame_url)
+    : render_frame_host_id_(render_frame_host_id),
+      presentation_url_(presentation_url),
+      frame_url_(frame_url) {}
+
+PresentationRequest::~PresentationRequest() = default;
+
+bool PresentationRequest::Equals(const PresentationRequest& other) const {
+  return render_frame_host_id_ == other.render_frame_host_id_ &&
+         presentation_url_ == other.presentation_url_ &&
+         frame_url_ == other.frame_url_;
+}
+
+MediaSource PresentationRequest::GetMediaSource() const {
+  return MediaSourceForPresentationUrl(presentation_url_);
+}
+
+}  // namespace media_router