Add mojo interface+impl for audio stream control.

media/mojo/services/mojo_audio_output.cc

+// 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.
+
+#include "media/mojo/services/mojo_audio_output.h"
+
+#include <memory>
+#include <utility>
+
+#include "base/callback_helpers.h"
+#include "base/memory/shared_memory.h"
+#include "base/sync_socket.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+
+namespace media {
+
+MojoAudioOutput::MojoAudioOutput(
+    mojom::AudioOutputRequest request,
+    CreateDelegateCallback create_delegate_callback,
+    StreamCreatedCallback stream_created_callback,
+    base::OnceClosure deleter_callback)
+    : stream_created_callback_(std::move(stream_created_callback)),
+      deleter_callback_(std::move(deleter_callback)),
+      binding_(this, std::move(request)),
+      delegate_(std::move(create_delegate_callback).Run(this)) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(deleter_callback_);
+  // |this| owns |binding_|, so unretained is safe.
+  binding_.set_connection_error_handler(
+      base::Bind(&MojoAudioOutput::OnError, base::Unretained(this)));
+}
+
+MojoAudioOutput::~MojoAudioOutput() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void MojoAudioOutput::Play() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnPlayStream();
+}
+
+void MojoAudioOutput::Pause() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnPauseStream();
+}
+
+void MojoAudioOutput::SetVolume(double volume) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (volume < 0 || volume > 1) {

[DaleCurtis, 2017/03/06 17:56:12]

Hmm, should this be a BadMessage instead which kills the renderer? I can't
remember if we tried this and found some client sending bad values or not
though.

[Max Morin, 2017/03/07 11:23:16]

I don't know if we get any bad volumes, I recall bad device_ids (not 64 hex
characters). However, we cannot use bad_message from the audio process later, so
I'm not sure we gain anything from adding it now. It also adds a dependency on
content.

+    LOG(ERROR) << "MojoAudioOutput::SetVolume(" << volume << ") out of range.";
+    OnError();
+    return;
+  }
+  delegate_->OnSetVolume(volume);
+}
+
+void MojoAudioOutput::OnStreamCreated(
+    int stream_id,

[DaleCurtis, 2017/03/06 17:56:12]

Unused? Still necessary?

[Max Morin, 2017/03/07 11:23:16]

It is part of the AudioOutputDelegate::EventHandler interface and
AudioRendererHost still needs it. It will be removed when ARH is removed (same
for the streamid in OnError).

+    base::SharedMemory* shared_memory,
+    base::CancelableSyncSocket* foreign_socket) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(stream_created_callback_);
+  DCHECK(shared_memory);
+  DCHECK(foreign_socket);
+
+  base::SharedMemoryHandle foreign_memory_handle =
+      base::SharedMemory::DuplicateHandle(shared_memory->handle());
+  DCHECK(base::SharedMemory::IsHandleValid(foreign_memory_handle));
+
+  mojo::ScopedSharedBufferHandle buffer_handle = mojo::WrapSharedMemoryHandle(
+      foreign_memory_handle, shared_memory->requested_size(), false);
+  mojo::ScopedHandle socket_handle =
+      mojo::WrapPlatformFile(foreign_socket->handle());
+
+  DCHECK(buffer_handle.is_valid());
+  DCHECK(socket_handle.is_valid());
+
+  base::ResetAndReturn(&stream_created_callback_)
+      .Run(std::move(buffer_handle), std::move(socket_handle));
+}
+
+void MojoAudioOutput::OnStreamError(int stream_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  OnError();
+}
+
+void MojoAudioOutput::OnError() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(deleter_callback_);
+  // Destroys |this|.
+  std::move(deleter_callback_).Run();
+}
+
+}  // namespace media