Media Remoting: Add RemotingController.

media/remoting/remoting_controller.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_CONTROLLER_H_
+#define MEDIA_REMOTING_REMOTING_CONTROLLER_H_
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/media_observer.h"
+#include "media/mojo/interfaces/remoting.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+// This class does the following:
+// 1) Sends/Receives messages from/to Remoter;
+// 2) Monitors player events as a MediaObserver;
+// 3) May trigger the switch of the media renderer between local playback
+// and remoting.
+//
+namespace media {
+
+class RemotingController final : public MediaObserver,
+                                 public mojom::RemotingSource {
+ public:
+  RemotingController(mojom::RemotingSourceRequest source_request,
+                     mojom::RemoterPtr remoter);
+  ~RemotingController() override;
+
+  // RemotingSource implementations.
+  void OnSinkAvailable() override;
+  void OnSinkGone() override;
+  // This is called when remoting is started successfully. Note: Only one video
+  // element can start remoting successfully at one time. The current
+  // logic is the first come first serve. This logic might be changed in future.

[xhwang, 2016/10/05 05:27:53]

Usually for overrides, we don't have extra comments. If we need comment for the
interface, it should be in mojom::RemotingSource. If it's an implementation
detail comment, it should be in the cc file.

[xjz, 2016/10/05 17:24:24]

Removed this comment here. This is controled by browser, and the comment is
already there: chrome/browser/media/cast_remoting_connector.h

+  void OnStarted() override;
+  void OnStartFailed(mojom::RemotingStartFailReason reason) override;
+  void OnMessageFromSink(const std::vector<uint8_t>& message) override;
+  void OnStopped(mojom::RemotingStopReason reason) override;
+
+  // MediaObserver implementations.
+  // This is called when the video element or its ancestor enters full screen.
+  // We currently use this as an indicator for immersive playback. May add other
+  // criteria (e.g. the actual display width/height of the video element) in
+  // future.
+  void OnEnteredFullscreen() override;
+  void OnExitedFullscreen() override;
+  void OnSetCdm(CdmContext* cdm_context) override;
+  void OnMetadata(const PipelineMetadata& metadata) override;
+
+  using SwitchRendererCallback = base::Callback<void()>;
+  void SetSwitchRendererCallback(const SwitchRendererCallback& cb);
+
+  // Tells which renderer should be used.
+  bool is_remoting() const {
+    DCHECK(task_runner_->BelongsToCurrentThread());
+    return is_remoting_;
+  }
+
+  base::WeakPtr<RemotingController> GetWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
+ private:
+  bool IsVideoConfigSupported();
+  bool IsAudioConfigSupported();
+
+  // Helper to decide whether to enter or leave Remoting mode.
+  bool ShouldBeRemoting();
+
+  // Determines whether to enter or leave Remoting mode and switches if
+  // necessary.
+  void UpdateAndMaybeSwitch();
+
+  // Indicates if this media element or its ancestor enters full screen.
+  bool is_fullscreen_ = false;
+
+  // Indicates the remoting sink availablity.
+  bool is_sink_available_ = false;
+
+  // Indicates if remoting is started.
+  bool is_remoting_ = false;
+
+  // Current audio/video config.
+  VideoDecoderConfig video_decoder_config_;
+  AudioDecoderConfig audio_decoder_config_;
+  bool has_audio_ = false;
+  bool has_video_ = false;
+
+  // The callback to switch the media renderer.
+  SwitchRendererCallback switch_renderer_cb_;
+
+  mojo::Binding<mojom::RemotingSource> binding_;
+  mojom::RemoterPtr remoter_;
+
+  // TODO(xjz): Add a media thread task runner for the received RPC messages for
+  // remoting media renderer in the up-coming change.
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  base::WeakPtrFactory<RemotingController> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemotingController);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_REMOTING_REMOTING_CONTROLLER_H_