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

content/renderer/media/audio_output_client.h

Index: content/renderer/media/audio_output_client.h
diff --git a/content/renderer/media/audio_output_client.h b/content/renderer/media/audio_output_client.h
new file mode 100644
index 0000000000000000000000000000000000000000..9b9c73d8f12bcfc3ff4cfef76f61018a26b616f6
--- /dev/null
+++ b/content/renderer/media/audio_output_client.h
@@ -0,0 +1,120 @@
+// 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_RENDERER_MEDIA_AUDIO_OUTPUT_CLIENT_H_
+#define CONTENT_RENDERER_MEDIA_AUDIO_OUTPUT_CLIENT_H_
+
+#include <map>
+
+#include "base/files/file.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/shared_memory_handle.h"
+#include "base/sync_socket.h"
+#include "base/threading/thread_checker.h"
+#include "content/common/content_export.h"
+#include "media/mojo/interfaces/audio_output.mojom.h"
+#include "mojo/edk/embedder/embedder.h"
+#include "mojo/public/c/system/buffer.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+#include "mojo/public/cpp/system/handle.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace media {
+class AudioParameters;
+}
+
+namespace content {
+
+class AudioMessageFilter;
+class ServiceRegistry;
+
+class CONTENT_EXPORT AudioOutputClient {

[mcasas, 2016/04/29 18:29:01]

Please add class comments, including the
threading model. I see methods OnMainThread(),
OnIoThread() and without thread indication.
Per thread in use, you should strive for
having a 
DCHECK(..._thread_task_runner_->BelongsToCurrentThread());
or
DCHECK(...thread_checker().CalledOnValidThread());
to document in-code where is the method
being called.

+ public:
+  typedef std::map<int,
+                   std::unique_ptr<media::interfaces::AudioOutputStreamPtr>>
+      ScopedAudioOutputStreamPtrMap;

[mcasas, 2016/04/29 18:29:01]

using ScopedAudioOutputStreamPtrMap = ...
?

[rchtara, 2016/05/23 16:38:18]

Done.

+
+  // Create a Mojo Audio Output Client. It's going to be created by

[mcasas, 2016/04/29 18:29:01]

Method documentation are descriptive:
s/Create/Creates/, here and throughout.

+  // RenderThreadImpl::init and be bound to RenderThread. This means that all

[mcasas, 2016/04/29 18:29:01]

init()

[rchtara, 2016/05/23 16:38:18]

Done.

+  // future Mojo service calls and all Mojo callbacks are going to be
+  // performed on the RenderThread.
+  explicit AudioOutputClient(
+      ServiceRegistry* service_registry,
+      scoped_refptr<AudioMessageFilter> audio_message_filter);
+
+  ~AudioOutputClient();
+
+  // Create stream by calling the AudioOutput.CreateStream Mojo interface
+  // function using the Mojo service. This function could be called on any
+  // thread and is going to call CreateStreamOnMainThread in the RenderThread.
+  void CreateStream(int stream_id,
+                    int render_frame_id,
+                    const media::AudioParameters& params);
+
+  // Create stream by calling the AudioOutput.CreateStream Mojo interface
+  // function using the Mojo service. This function could be called on just
+  // the RenderThread.
+  void CreateStreamOnMainThread(int stream_id,
+                                int render_frame_id,
+                                const media::AudioParameters& params);
+
+  // Callback for AudioOutput.CreateStream which contains information about
+  // the new created stream. Called on RenderThread. This function is going to
+  // notify the |audio_message_filter_| of the stream creation by calling
+  // StreamCreated. StreamCreated could only be ran on |io_task_runner_| and
+  // this is why CreateStreamOnIOThread is going to be used to do that.
+  void CreateStreamCallback(int stream_id,
+                            media::interfaces::AudioOutputStreamPtr stream,
+                            mojo::ScopedSharedBufferHandle shared_buffer,
+                            mojo::ScopedHandle socket_descriptor);
+
+  // Notify  the |audio_message_filter_| of the stream creation. Can only be
+  // called on |io_task_runner_|.
+  void CreateStreamOnIOThread(
+      media::interfaces::AudioOutputStreamPtr* const stream,
+      base::SharedMemoryHandle handle,
+      base::SyncSocket::TransitDescriptor socket_descriptor,
+      uint32_t length);
+
+  // Close stream by calling the AudioOutputStream.Close Mojo interface
+  // function using the Mojo service. This function could be called on any
+  // thread and is going to call CloseStreamOnMainThread in the RenderThread.
+  void CloseStream(int stream_id);
+
+  // Close stream by calling the AudioOutputStream.Close Mojo interface
+  // function using the Mojo service. This function could be called on just the
+  // RenderThread.
+  void CloseStreamOnMainThread(int stream_id);
+
+  // Called when there is an error with AudioOutputStream Mojo interface in
+  // the renderer. This function is going to call ReportErrorOnIOThread in the
+  // RenderThread.
+  void OnStreamError(int stream_id);

[mcasas, 2016/04/29 18:29:01]

Can be private I believe. Check the
other methods and make private as many
as possible.

[rchtara, 2016/05/23 16:38:18]

Done.

+
+  // Notify  the |audio_message_filter_| of a stream error. Can only be called
+  // on |io_task_runner_|.
+  void ReportErrorOnIOThread(int stream_id);
+
+ private:
+  // Mojo connection error handler.
+  void OnConnectionError();
+
+  scoped_refptr<AudioMessageFilter> audio_message_filter_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;

[mcasas, 2016/04/29 18:29:01]

const.

Leave a blank line before the next comment,
however, it being superfluous, just remove it.

[rchtara, 2016/05/23 16:38:19]

Done.

+  // The Mojo service.
+  media::interfaces::AudioOutputPtr service_;
+  ScopedAudioOutputStreamPtrMap streams_;
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputClient);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_AUDIO_OUTPUT_CLIENT_H_