Switch stream creation and closing in Chrome audio rendering from IPC to Mojo

content/browser/media/audio_output_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 CONTENT_BROWSER_MEDIA_AUDIO_OUTPUT_IMPL_H_
+#define CONTENT_BROWSER_MEDIA_AUDIO_OUTPUT_IMPL_H_
+
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "content/browser/renderer_host/media/audio_renderer_host.h"
+#include "content/common/content_export.h"
+#include "media/mojo/interfaces/audio_output.mojom.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace base {
+class FilePath;
+}
+
+namespace content {
+// This class implements AudioOutputStream Mojo interface. It will be used
+// by the AudioOutputClient to perform operations on audio output streams.
+// AudioOutputClient will perform operations remotely on the
+// AudioOutputStreamPtr and Mojo will transfer them to AudioOutputStreamImpl.
+// Owned by AudioOutputImpl.
+class CONTENT_EXPORT AudioOutputStreamImpl
+    : public media::mojom::AudioOutputStream {
+ public:
+  AudioOutputStreamImpl(media::mojom::AudioOutputStreamRequest request,
+                        int stream_id,
+                        AudioRendererHost* audio_renderer_host);
+
+  ~AudioOutputStreamImpl() override;
+
+ private:
+  // AudioOutputStream interface implementation.
+  void Close() override;
+
+  mojo::StrongBinding<media::mojom::AudioOutputStream> binding_;
+  int stream_id_;
+  // AudioRendererHost is ref counted and AudioOutputImpl holds a reference to
+  // it. And because all AudioOutputStreamImpl instances will be owned by
+  // AudioOutputImpl too, it's safe to access AudioRendererHost from
+  // AudioOutputStreamImpl.
+  // The only issue that could happen is during AudioOutputStreamImpl
+  // destructor. AudioRendererHost cannot access from there.
+  AudioRendererHost* audio_renderer_host_;
+};
+
+// This class implements AudioOutput Mojo interface. It will be used
+// by the AudioOutputClient to perform operations on audio output streams.
+// AudioOutputClient is going to perform operations remotely and Mojo will
+// transfer them to AudioOutputImpl.
+// This class must always be accessed from the creation thread.
+class CONTENT_EXPORT AudioOutputImpl
+    : NON_EXPORTED_BASE(public media::mojom::AudioOutput) {
+ public:
+  explicit AudioOutputImpl(scoped_refptr<AudioRendererHost> audio_renderer_host,
+                           media::mojom::AudioOutputRequest request);
+
+  ~AudioOutputImpl() override;
+
+  // Create a Mojo service.
+  static void CreateService(
+      scoped_refptr<AudioRendererHost> audio_renderer_host,
+      media::mojom::AudioOutputRequest request);
+  // Initialize Mojo service on the IO thread. The service is bound to the
+  // IO thread so future Mojo calls performed by the AudioOutputClient to the
+  // AudioOutput interface will be run on that thread.
+  // There are a lot of dependencies used in audio output that require to be
+  // called on the IO thread, this is why we initialize Mojo service on this
+  // thread. There is a plan to enable these dependencies to run on another
+  // thread and move the Mojo service to this thread as IO thread is very
+  // performance sensitive and we want to move stuff off it.
+  static void CreateServiceOnIOThread(
+      scoped_refptr<AudioRendererHost> audio_renderer_host,
+      media::mojom::AudioOutputRequest request);
+
+  // Called by AudioRendererHost::DoCompleteCreation to create the streams.
+  media::mojom::AudioOutputStreamPtr StreamFactory(
+      int stream_id,
+      AudioRendererHost* audio_renderer_host);
+
+ private:
+  // AudioOutput interface implementation.
+  void CreateStream(int stream_id,
+                    int render_frame_id,
+                    media::interfaces::AudioParametersPtr params,
+                    const CreateStreamCallback& callback) override;
+
+  scoped_refptr<AudioRendererHost> audio_renderer_host_;
+  mojo::StrongBinding<AudioOutput> binding_;
+  std::map<int, std::unique_ptr<AudioOutputStreamImpl>> stream_impls_;
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEDIA_AUDIO_OUTPUT_IMPL_H_