Media Remoting: Add remoting control logic for encrypted contents.

media/remoting/remoting_source_impl.h

+// Copyright 2016 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 MEDIA_REMOTING_REMOTING_SOURCE_IMPL_H_
+#define MEDIA_REMOTING_REMOTING_SOURCE_IMPL_H_
+
+#include <vector>
+
+#include "base/threading/thread_checker.h"
+#include "media/mojo/interfaces/remoting.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace media {
+
+enum RemotingSessionState {
+  // Remoting sink is not available. Can't start remoting.
+  SESSION_UNAVAILABLE,
+  // Remoting sink is available, Can start remoting.
+  SESSION_CAN_START,
+  // Starting a remoting session.
+  SESSION_STARTING,
+  // Remoting session is successively started.
+  SESSION_STARTED,
+  // Stopping the session.
+  SESSION_STOPPING,
+  // Remoting session is permanently stopped. This state indicates that the
+  // video stack cannot continue operation. For example, if a remoting session
+  // involving CDM content was stopped, there is no way to continue playback
+  // because the CDM is required but is no longer available.
+  SESSION_PERMANENTLY_STOPPED,
+};
+
+// Maintains a single remoting session for multiple clients. The session will
+// start remoting when receiving the first request. Once remoting is started,
+// it will be stopped when any of the following happens:
+// 1) Receives the request from any client to stop remoting.
+// 2) Remote sink is gone.
+// 3) Any client requests to permanently terminate the session.
+// 4) All clients are destroyed.
+//
+// This class is ref-counted because, in some cases, an instance will have
+// shared ownership between RemotingRendererController and
+// RemotingCdmController.
+class RemotingSourceImpl final
+    : public mojom::RemotingSource,
+      public base::RefCountedThreadSafe<RemotingSourceImpl> {
+ public:
+  class Client {
+   public:
+    // Get notified whether the remoting session is successively started.
+    virtual void OnStarted(bool success) = 0;
+    // Get notified when session state changes.
+    virtual void OnSessionStateChanged() = 0;
+  };
+
+  RemotingSourceImpl(mojom::RemotingSourceRequest source_request,
+                     mojom::RemoterPtr remoter);
+
+  // Get the current session state.
+  RemotingSessionState state() const {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    return state_;
+  }
+
+  // RemotingSource implementations.
+  void OnSinkAvailable() override;
+  void OnSinkGone() override;
+  void OnStarted() override;
+  void OnStartFailed(mojom::RemotingStartFailReason reason) override;
+  void OnMessageFromSink(const std::vector<uint8_t>& message) override;
+  void OnStopped(mojom::RemotingStopReason reason) override;
+
+  // Requests to start remoting. Will try start a remoting session if not
+  // started yet. |client| will get informed whether the session is
+  // successifully started throught OnStarted().
+  void StartRemoting(Client* client);
+
+  // Requests to stop the current remoting session if started. When the session
+  // is stopping, all clients will get notified.
+  void StopRemoting(Client* client);
+
+  // Permanently terminates the current remoting session.
+  void ShutDown();
+
+  // Add/remove a client to/from |clients_|.
+  // Remoting session will be stopped if all clients are gone.
+  void AddClient(Client* client);
+  void RemoveClient(Client* client);
+
+ private:
+  friend class base::RefCountedThreadSafe<RemotingSourceImpl>;
+  ~RemotingSourceImpl() override;
+
+  // Updates the current session state and notifies all the clients if state
+  // changes.
+  void UpdateAndNotifyState(RemotingSessionState state);
+
+  const mojo::Binding<mojom::RemotingSource> binding_;
+  const mojom::RemoterPtr remoter_;
+
+  // The current state.
+  RemotingSessionState state_ = RemotingSessionState::SESSION_UNAVAILABLE;
+
+  // Clients are added/removed to/from this list by calling Add/RemoveClient().
+  std::vector<Client*> clients_;
+
+  // This is used to check all the methods are called on the current thread in
+  // debug builds.
+  base::ThreadChecker thread_checker_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_REMOTING_REMOTING_SOURCE_IMPL_H_