Factor out authorization from AudioRendererHost.

content/browser/renderer_host/media/audio_output_authorization_handler.cc

+// 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.
+
+#include "content/browser/renderer_host/media/audio_output_authorization_handler.h"
+
+#include "base/task_runner_util.h"
+#include "content/browser/renderer_host/media/audio_input_device_manager.h"
+#include "content/public/browser/media_device_id.h"
+#include "media/base/limits.h"
+
+namespace {
+
+bool IsValidDeviceId(const std::string& device_id) {
+  static const std::string::size_type kValidLength = 64;
+
+  if (device_id.empty() ||
+      device_id == media::AudioDeviceDescription::kDefaultDeviceId ||

[o1ka, 2016/10/27 13:58:09]

l.17 and 18 are AudioDeviceDescription::IsDefaultDevice()

[Max Morin, 2016/10/28 11:16:07]

Done.

+      device_id == media::AudioDeviceDescription::kCommunicationsDeviceId) {
+    return true;
+  }
+
+  if (device_id.length() != kValidLength)
+    return false;
+
+  for (const char& c : device_id) {
+    if ((c < 'a' || c > 'f') && (c < '0' || c > '9'))
+      return false;
+  }
+
+  return true;
+}
+
+void MaybeFixAudioParameters(media::AudioParameters* params) {
+  // If the number of output channels is greater than the maximum, use the
+  // maximum allowed value. Hardware channels are ignored upstream, so it is
+  // better to report a valid value if this is the only problem.
+  if (params->channels() > media::limits::kMaxChannels)
+    params->set_channels_for_discrete(media::limits::kMaxChannels);
+
+  // If hardware parameters are still invalid, use dummy parameters with
+  // fake audio path and let the client handle the error.
+  if (!params->IsValid())
+    *params = media::AudioParameters::UnavailableDeviceParams();
+}
+
+media::AudioParameters GetDeviceParametersOnDeviceThread(
+    const std::string& unique_id) {
+  media::AudioManager* audio_manager = media::AudioManager::Get();
+  DCHECK(audio_manager->GetTaskRunner()->BelongsToCurrentThread());
+
+  if (media::AudioDeviceDescription::IsDefaultDevice(unique_id))
+    return audio_manager->GetDefaultOutputStreamParameters();
+  return audio_manager->GetOutputStreamParameters(unique_id);
+}
+
+}  // namespace
+
+namespace content {
+
+AudioOutputAuthorizationHandler::AudioOutputAuthorizationHandler(
+    MediaStreamManager* media_stream_manager,
+    int render_process_id,
+    const std::string& salt)
+    : media_stream_manager_(media_stream_manager),
+      render_process_id_(render_process_id),
+      salt_(salt),
+      bad_message_handler_(),
+      weak_factory(this) {
+  DCHECK(media_stream_manager_);
+}
+
+AudioOutputAuthorizationHandler::~AudioOutputAuthorizationHandler() = default;
+
+void AudioOutputAuthorizationHandler::RequestDeviceAuthorization(
+    int render_frame_id,
+    int session_id,
+    const std::string& device_id,
+    const url::Origin& security_origin,
+    AuthorizationCompletedCallback cb) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (!IsValidDeviceId(device_id)) {
+    cb.Run(media::OUTPUT_DEVICE_STATUS_ERROR_NOT_FOUND,
+           media::AudioParameters::UnavailableDeviceParams(), std::string());
+    return;
+  }
+
+  // If |session_id| should be used for output device selection and such output
+  // device is found, reuse the input device permissions.
+  if (media::AudioDeviceDescription::UseSessionIdToSelectDevice(session_id,
+                                                                device_id)) {
+    const StreamDeviceInfo* info =
+        media_stream_manager_->audio_input_device_manager()
+            ->GetOpenedDeviceInfoById(session_id);
+    if (info) {
+      media::AudioParameters output_params(
+          media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
+          static_cast<media::ChannelLayout>(
+              info->device.matched_output.channel_layout),
+          info->device.matched_output.sample_rate, 16,
+          info->device.matched_output.frames_per_buffer);
+      output_params.set_effects(info->device.matched_output.effects);
+      MaybeFixAudioParameters(&output_params);
+
+      cb.Run(media::OUTPUT_DEVICE_STATUS_OK, output_params,
+             GetHMACForMediaDeviceID(salt_, security_origin,
+                                     info->device.matched_output_device_id));
+      return;
+    }
+  }
+
+  CheckOutputDeviceAccess(std::move(cb), render_frame_id, device_id,
+                          security_origin);
+}
+
+void AudioOutputAuthorizationHandler::CheckOutputDeviceAccess(
+    AuthorizationCompletedCallback cb,

[o1ka, 2016/10/27 13:58:09]

Everywhere in this class: Usually callback is the last parameter, is there a
specific reason you put it at the beginning?

[Max Morin, 2016/10/28 11:16:07]

I was not aware of this convention. Making it the very last won't work (because
unbound parameters have to be last), but I could make it second last or somewhat
late in the parameter list.

[o1ka, 2016/10/28 13:18:40]

Ok, it's fine. "Usually" means just "usually" :)

+    int render_frame_id,
+    const std::string& device_id,
+    const url::Origin& security_origin) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  // Check security origin if nondefault device is requested.
+  // Ignore check for default device, which is always authorized.
+  if (!media::AudioDeviceDescription::IsDefaultDevice(device_id) &&
+      !MediaStreamManager::IsOriginAllowed(render_process_id_,
+                                           security_origin)) {
+    if (!bad_message_handler_.is_null())
+      bad_message_handler_.Run(bad_message::ARH_UNAUTHORIZED_URL);
+    return;
+  }
+
+  if (media::AudioDeviceDescription::IsDefaultDevice(device_id)) {
+    AccessChecked(std::move(cb), nullptr, device_id, security_origin, true);
+  } else {
+    // Check that MediaStream device permissions have been granted,
+    // hence the use of a MediaStreamUIProxy.
+    std::unique_ptr<MediaStreamUIProxy> ui_proxy = MediaStreamUIProxy::Create();
+
+    // Use MEDIA_DEVICE_AUDIO_CAPTURE instead of MEDIA_DEVICE_AUDIO_OUTPUT
+    // because MediaStreamUIProxy::CheckAccess does not currently support
+    // MEDIA_DEVICE_AUDIO_OUTPUT.
+    // TODO(guidou): Change to MEDIA_DEVICE_AUDIO_OUTPUT when support becomes
+    // available. http://crbug.com/498675
+    ui_proxy->CheckAccess(
+        security_origin, MEDIA_DEVICE_AUDIO_CAPTURE, render_process_id_,
+        render_frame_id,
+        base::Bind(&AudioOutputAuthorizationHandler::AccessChecked,
+                   weak_factory.GetWeakPtr(), std::move(cb),
+                   base::Passed(&ui_proxy), device_id, security_origin));
+  }
+}
+
+void AudioOutputAuthorizationHandler::AccessChecked(
+    AuthorizationCompletedCallback cb,
+    std::unique_ptr<MediaStreamUIProxy> ui_proxy,
+    const std::string& device_id,
+    const url::Origin& security_origin,
+    bool have_access) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (!have_access) {
+    cb.Run(media::OUTPUT_DEVICE_STATUS_ERROR_NOT_AUTHORIZED,
+           media::AudioParameters::UnavailableDeviceParams(), std::string());
+    return;
+  }
+
+  // For default device, read output parameters directly. Nondefault devices
+  // require translation first.
+  if (media::AudioDeviceDescription::IsDefaultDevice(device_id)) {
+    base::PostTaskAndReplyWithResult(
+        media::AudioManager::Get()->GetTaskRunner(), FROM_HERE,
+        base::Bind(&GetDeviceParametersOnDeviceThread,
+                   media::AudioDeviceDescription::kDefaultDeviceId),
+        base::Bind(&AudioOutputAuthorizationHandler::DeviceParametersReceived,
+                   weak_factory.GetWeakPtr(), std::move(cb), true,
+                   media::AudioDeviceDescription::kDefaultDeviceId));
+  } else {
+    MediaDevicesManager::BoolDeviceTypes devices_to_enumerate;
+    devices_to_enumerate[MEDIA_DEVICE_TYPE_AUDIO_OUTPUT] = true;
+    media_stream_manager_->media_devices_manager()->EnumerateDevices(
+        devices_to_enumerate,
+        base::Bind(&AudioOutputAuthorizationHandler::TranslateDeviceID,
+                   weak_factory.GetWeakPtr(), std::move(cb), device_id,
+                   security_origin));
+  }
+}
+
+void AudioOutputAuthorizationHandler::TranslateDeviceID(
+    AuthorizationCompletedCallback cb,
+    const std::string& device_id,
+    const url::Origin& security_origin,
+    const MediaDeviceEnumeration& enumeration) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(!media::AudioDeviceDescription::IsDefaultDevice(device_id));
+  for (const MediaDeviceInfo& device_info :
+       enumeration[MEDIA_DEVICE_TYPE_AUDIO_OUTPUT]) {
+    if (content::DoesMediaDeviceIDMatchHMAC(salt_, security_origin, device_id,
+                                            device_info.device_id)) {
+      base::PostTaskAndReplyWithResult(
+          media::AudioManager::Get()->GetTaskRunner(), FROM_HERE,
+          base::Bind(&GetDeviceParametersOnDeviceThread, device_info.device_id),
+          base::Bind(&AudioOutputAuthorizationHandler::DeviceParametersReceived,
+                     weak_factory.GetWeakPtr(), std::move(cb), true,
+                     device_info.device_id));
+      return;
+    }
+  }
+  DeviceParametersReceived(std::move(cb), false, std::string(),
+                           media::AudioParameters::UnavailableDeviceParams());
+}
+
+void AudioOutputAuthorizationHandler::DeviceParametersReceived(
+    AuthorizationCompletedCallback cb,
+    bool device_found,
+    const std::string& unique_id,
+    media::AudioParameters output_params) {

[o1ka, 2016/10/27 13:58:08]

const ref, and make a copy only if needed (as in the original code)?

[Max Morin, 2016/10/28 11:16:07]

This specific function needs to mutate the parameters (call to
MaybeFixAudioParameters), so I leave this one as passed by value. I changed to
const ref everywhere else.

[o1ka, 2016/10/28 13:18:40]

Ok, if this is your preference - just make a comment in the header.

+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (!device_found) {
+    cb.Run(media::OUTPUT_DEVICE_STATUS_ERROR_NOT_FOUND,
+           media::AudioParameters::UnavailableDeviceParams(), "");
+    return;
+  }
+
+  MaybeFixAudioParameters(&output_params);
+  cb.Run(media::OUTPUT_DEVICE_STATUS_OK, output_params, unique_id);
+}
+
+}  // namespace content