[Media Router] Use DialMediaSinkService in MediaRouterMojoImpl

chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h

+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner_helpers.h"
+#include "chrome/common/media_router/discovery/media_sink_service.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace media_router {
+
+class DialMediaSinkServiceImpl;
+
+// A wrapper class of DialMediaSinkService handling thread hopping between UI
+// and IO threads. This class is thread safe. Public APIs should be invoked on
+// UI thread. It then post tasks to IO thread and invoke them on underlying
+// DialMediaSinkService instance.
+class DialMediaSinkServiceProxy
+    : public MediaSinkService,
+      public base::RefCountedThreadSafe<
+          DialMediaSinkServiceProxy,
+          content::BrowserThread::DeleteOnIOThread> {
+ public:
+  // |callback| is invoked on the UI thread when sinks are discovered.
+  // |context| is browser context.
+  DialMediaSinkServiceProxy(
+      const MediaSinkService::OnSinksDiscoveredCallback& callback,
+      content::BrowserContext* context);
+
+  // Starts discovery of DIAL devices on IO thread.
+  void Start() override;
+
+  // Stops discovery of DIAL devices on IO thread. The callback passed to
+  // Start() is cleared.

[Kevin M, 2017/05/24 00:52:55]

We should document somewhere in this header (maybe at the top?) that Stop() must
be called, otherwise the proxy will never die.

[zhaobin, 2017/05/24 17:45:51]

Done.

+  void Stop() override;
+
+  void SetDialMediaSinkServiceForTest(
+      std::unique_ptr<DialMediaSinkServiceImpl> dial_media_sink_service);
+
+ private:
+  friend class DialMediaSinkServiceProxyTest;
+  friend class base::DeleteHelper<DialMediaSinkServiceProxy>;
+  friend struct content::BrowserThread::DeleteOnThread<
+      content::BrowserThread::IO>;
+  friend class base::RefCountedThreadSafe<DialMediaSinkServiceProxy>;
+
+  ~DialMediaSinkServiceProxy() override;
+
+  // Starts DIAL discovery.
+  void StartOnIOThread();
+
+  // Stops DIAL discovery.
+  void StopOnIOThread();
+
+  // Callback passed to |dial_media_sink_service_| ctor. When invoked, post task
+  // to UI thread and invoke |sink_discovery_callback_|.
+  void OnSinksDiscoveredOnIOThread(std::vector<MediaSinkInternal> sinks);
+
+ private:
+  std::unique_ptr<DialMediaSinkServiceImpl> dial_media_sink_service_;
+
+  net::URLRequestContextGetter* request_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(DialMediaSinkServiceProxy);
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_