Add a mojo implementation of AudioOutputIPC.

content/renderer/media/mojo_audio_output_ipc.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 "content/renderer/media/mojo_audio_output_ipc.h"
+
+#include <utility>
+
+#include "content/renderer/media/audio_ipc_factory.h"
+#include "media/audio/audio_device_description.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+
+namespace content {
+
+namespace {
+
+void TrivialAuthorizedCallback(media::OutputDeviceStatus,
+                               const media::AudioParameters&,
+                               const std::string&) {}
+
+}  // namespace
+
+MojoAudioOutputIPC::MojoAudioOutputIPC(int frame_id)
+    : frame_id_(frame_id), weak_factory_(this) {
+  thread_checker_.DetachFromThread();
+}
+
+MojoAudioOutputIPC::~MojoAudioOutputIPC() {
+  // No thread check.
+  // Destructing |weak_factory_| on any thread is safe since it's not used after
+  // the final call to CloseStream.

[o1ka, 2017/04/20 10:36:00]

Could you please clarify the comment?

[o1ka, 2017/04/20 10:36:00]

* if CloseStream() has been called. DCHECKs for that?

[Max Morin, 2017/05/05 13:10:58]

Done.

[Max Morin, 2017/05/05 13:10:59]

Done.

+}
+
+media::mojom::AudioOutputStreamProviderRequest
+MojoAudioOutputIPC::MakeProviderRequest(
+    media::AudioOutputIPCDelegate* delegate) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!stream_provider_.is_bound());
+  media::mojom::AudioOutputStreamProviderRequest request =
+      mojo::MakeRequest(&stream_provider_);
+
+  // Unretained is safe because |delegate| owns |this|.
+  stream_provider_.set_connection_error_handler(base::Bind(
+      &media::AudioOutputIPCDelegate::OnError, base::Unretained(delegate)));
+  return request;
+}
+
+void MojoAudioOutputIPC::RequestDeviceAuthorization(
+    media::AudioOutputIPCDelegate* delegate,
+    int session_id,
+    const std::string& device_id,
+    const url::Origin& security_origin) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(delegate);
+  DCHECK(!stream_provider_.is_bound());
+  DCHECK(!stream_.is_bound());
+  auto* factory = AudioIPCFactory::get()->GetRemoteFactory(frame_id_);
+  if (!factory) {
+    LOG(ERROR) << "No factory is registered for " << frame_id_;
+    delegate->OnIPCClosed();  // deletes |this|.
+    return;
+  }
+
+  // Unretained is safe because |delegate| owns |this|.
+  factory->RequestDeviceAuthorization(
+      MakeProviderRequest(delegate), session_id, device_id,
+      base::Bind(&MojoAudioOutputIPC::RecievedDeviceAuthorization,
+                 weak_factory_.GetWeakPtr(), delegate));
+}
+
+void MojoAudioOutputIPC::RecievedDeviceAuthorization(
+    media::AudioOutputIPCDelegate* delegate,
+    media::OutputDeviceStatus status,
+    const media::AudioParameters& params,
+    const std::string& device_id) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate->OnDeviceAuthorized(status, params, device_id);
+}
+
+void MojoAudioOutputIPC::CreateStream(media::AudioOutputIPCDelegate* delegate,
+                                      const media::AudioParameters& params) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(delegate);
+  DCHECK(!stream_.is_bound());
+  if (!stream_provider_.is_bound()) {

[o1ka, 2017/04/20 10:35:59]

M.b. would be more readable to have
AuthorizationRequested()/StreamCreationRequested()?

[Max Morin, 2017/05/05 13:10:59]

Done.

+    // No authorization requested yet. Request one for the default device.
+    // This also means we shouldn't callback to the delegate for the reply.
+    auto* factory = AudioIPCFactory::get()->GetRemoteFactory(frame_id_);
+    if (!factory) {
+      LOG(ERROR) << "No factory is registered for " << frame_id_;
+      delegate->OnIPCClosed();  // deletes |this|.
+      return;
+    }
+
+    factory->RequestDeviceAuthorization(

[o1ka, 2017/04/20 10:35:59]

WDYT about making a helper function and using it here and in
RequestDeviceAuthorization() ?

[Max Morin, 2017/05/05 13:10:59]

Looks more complex (since it returns early if there is no factory, there would
have to be some logic to take care of that).

+        MakeProviderRequest(delegate), 0,
+        media::AudioDeviceDescription::kDefaultDeviceId,
+        base::Bind(&TrivialAuthorizedCallback));
+  }
+
+  // Since the callback won't fire if the binding is gone, unretained is safe.

[o1ka, 2017/04/20 10:35:59]

Which callback and which binding? It's hard for an unprepared reader :)

[Max Morin, 2017/05/05 13:10:58]

Done.

+  stream_provider_->Acquire(mojo::MakeRequest(&stream_), params,
+                            base::Bind(&MojoAudioOutputIPC::StreamCreated,
+                                       base::Unretained(this), delegate));
+
+  // Unretained is safe because |delegate| owns |this|.
+  stream_.set_connection_error_handler(base::Bind(
+      &media::AudioOutputIPCDelegate::OnError, base::Unretained(delegate)));
+}
+
+void MojoAudioOutputIPC::StreamCreated(
+    media::AudioOutputIPCDelegate* delegate,
+    mojo::ScopedSharedBufferHandle shared_memory,
+    mojo::ScopedHandle socket) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(socket.is_valid());
+  DCHECK(shared_memory.is_valid());
+
+  base::PlatformFile socket_handle;
+  mojo::UnwrapPlatformFile(std::move(socket), &socket_handle);
+
+  base::SharedMemoryHandle memory_handle;
+  bool read_only = false;
+  size_t memory_length = 0;
+  auto result = mojo::UnwrapSharedMemoryHandle(
+      std::move(shared_memory), &memory_handle, &memory_length, &read_only);
+  DCHECK_EQ(result, MOJO_RESULT_OK);
+  DCHECK(!read_only);
+
+  delegate->OnStreamCreated(memory_handle, socket_handle, memory_length);
+}
+
+void MojoAudioOutputIPC::PlayStream() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (stream_.is_bound())
+    stream_->Play();
+}
+
+void MojoAudioOutputIPC::PauseStream() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (stream_.is_bound())
+    stream_->Pause();
+}
+
+void MojoAudioOutputIPC::CloseStream() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  stream_provider_.reset();
+  stream_.reset();
+
+  // Make sure we don't send an authorization callback for this stream to the

[o1ka, 2017/04/20 10:36:00]

We need a comment explaining why we are never stuck waiting for authorization.
(Either authorization is signaled or OnIPCClosed() is called on every path?)

[Max Morin, 2017/05/05 13:10:59]

In this case, the AudioOutputDevice must take care of it. In general, see
comment in RequestDeviceAuthorization.

+  // delegate.
+  weak_factory_.InvalidateWeakPtrs();
+}
+
+void MojoAudioOutputIPC::SetVolume(double volume) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (stream_.is_bound())
+    stream_->SetVolume(volume);
+}
+
+}  // namespace content