[Presentation API] 1-UA presentation support + presenter APIs.

chrome/browser/media/router/render_frame_host_helper.h

Index: chrome/browser/media/router/render_frame_host_helper.h
diff --git a/chrome/browser/media/router/render_frame_host_helper.h b/chrome/browser/media/router/render_frame_host_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..70a788db86879736d894f352aa1d5332d16fea16
--- /dev/null
+++ b/chrome/browser/media/router/render_frame_host_helper.h
@@ -0,0 +1,21 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.

[mark a. foltz, 2015/10/12 21:56:10]

Maybe this should be named render_frame_host_id.h?

[imcheng, 2015/10/17 01:00:24]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_RENDER_FRAME_HOST_HELPER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_RENDER_FRAME_HOST_HELPER_H_
+
+#include <utility>
+
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_process_host.h"
+
+namespace media_router {
+
+using RenderFrameHostId =
+    std::pair<decltype(((content::RenderProcessHost*)nullptr)->GetID()),

[mark a. foltz, 2015/10/12 21:56:10]

Is decltype necessary here?  It seems to only be recommended for rare situations
like variadic templates.

https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/_zoNvZd_dSo

If the types of the ids get widened to long (which seems unlikely) you should
get a compile error when trying to assign them to pair<int, int>.

[imcheng, 2015/10/17 01:00:24]

Done.

+              decltype(((content::RenderFrameHost*)nullptr)->GetRoutingID())>;
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_RENDER_FRAME_HOST_HELPER_H_