app_shell: Do simple audio initialization.

extensions/shell/browser/shell_audio_controller_chromeos.cc

+// Copyright 2014 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 "extensions/shell/browser/shell_audio_controller_chromeos.h"
+
+#include <algorithm>
+
+#include "chromeos/audio/audio_device.h"
+
+namespace extensions {
+
+namespace {
+
+// Default output and input volume.
+const double kOutputVolumePercent = 100.0;
+const double kInputGainPercent = 100.0;
+
+// Returns a pointer to the device in |devices| with ID |node_id|, or NULL if it
+// isn't present.
+const chromeos::AudioDevice* GetDevice(const chromeos::AudioDeviceList& devices,
+                                       uint64 node_id) {
+  for (chromeos::AudioDeviceList::const_iterator it = devices.begin();
+       it != devices.end(); ++it) {
+    if (it->id == node_id)
+      return &(*it);
+  }
+  return NULL;
+}
+
+}  // namespace
+
+ShellAudioController::PrefHandler::PrefHandler() {}
+
+double ShellAudioController::PrefHandler::GetOutputVolumeValue(
+    const chromeos::AudioDevice* device) {
+  return kOutputVolumePercent;
+}
+
+double ShellAudioController::PrefHandler::GetInputGainValue(
+    const chromeos::AudioDevice* device) {
+  return kInputGainPercent;
+}
+
+void ShellAudioController::PrefHandler::SetVolumeGainValue(
+    const chromeos::AudioDevice& device,
+    double value) {}
+
+bool ShellAudioController::PrefHandler::GetMuteValue(
+    const chromeos::AudioDevice& device) {
+  return false;
+}
+void ShellAudioController::PrefHandler::SetMuteValue(
+    const chromeos::AudioDevice& device,
+    bool mute_on) {}
+
+bool ShellAudioController::PrefHandler::GetAudioCaptureAllowedValue() {
+  return true;
+}
+
+bool ShellAudioController::PrefHandler::GetAudioOutputAllowedValue() {
+  return true;
+}
+
+void ShellAudioController::PrefHandler::AddAudioPrefObserver(
+    chromeos::AudioPrefObserver* observer) {}
+
+void ShellAudioController::PrefHandler::RemoveAudioPrefObserver(
+    chromeos::AudioPrefObserver* observer) {}
+
+ShellAudioController::PrefHandler::~PrefHandler() {}
+
+ShellAudioController::ShellAudioController() {
+  chromeos::CrasAudioHandler::Get()->AddAudioObserver(this);
+  ActivateDevices();
+}
+
+ShellAudioController::~ShellAudioController() {
+  chromeos::CrasAudioHandler::Get()->RemoveAudioObserver(this);
+}
+
+void ShellAudioController::OnOutputVolumeChanged() {}
+
+void ShellAudioController::OnOutputMuteChanged() {}
+
+void ShellAudioController::OnInputGainChanged() {}
+
+void ShellAudioController::OnInputMuteChanged() {}
+
+void ShellAudioController::OnAudioNodesChanged() {
+  VLOG(1) << "Audio nodes changed";
+  ActivateDevices();
+}
+
+void ShellAudioController::OnActiveOutputNodeChanged() {}
+
+void ShellAudioController::OnActiveInputNodeChanged() {}
+
+void ShellAudioController::ActivateDevices() {
+  chromeos::CrasAudioHandler* handler = chromeos::CrasAudioHandler::Get();
+  chromeos::AudioDeviceList devices;
+  handler->GetAudioDevices(&devices);
+  sort(devices.begin(), devices.end(), chromeos::AudioDeviceCompare());
+
+  uint64 best_input = 0, best_output = 0;
+  for (chromeos::AudioDeviceList::const_reverse_iterator it = devices.rbegin();
+       it != devices.rend() && (!best_input || !best_output); ++it) {

[James Cook, 2014/08/27 23:18:33]

Would it be simpler to do two searches, one for best input and one for best
output? That might simplify the logic here.

[Daniel Erat, 2014/08/28 00:12:20]

hmm, that seems like it'd still be more code overall since c++ iterators are so
verbose. we can't use the c++11-style "for (auto &device : devices)" yet, can
we? (i don't know if there's any way to use them with reverse iterators in any
case.)

+    if (it->is_input && !best_input)
+      best_input = it->id;
+    else if (!it->is_input && !best_output)
+      best_output = it->id;
+  }
+
+  if (best_input && best_input != handler->GetActiveInputNode()) {
+    const chromeos::AudioDevice* device = GetDevice(devices, best_input);
+    DCHECK(device);
+    VLOG(1) << "Activating input device: " << device->ToString();
+    handler->SwitchToDevice(*device);
+  }
+  if (best_output && best_output != handler->GetActiveOutputNode()) {
+    const chromeos::AudioDevice* device = GetDevice(devices, best_output);
+    DCHECK(device);
+    VLOG(1) << "Activating output device: " << device->ToString();
+    handler->SwitchToDevice(*device);
+  }
+}

[James Cook, 2014/08/27 23:18:33]

How hard would it be to add a test for this class? Do we have enough test
support to at least construct an instance and tear it down?

[Daniel Erat, 2014/08/28 00:12:20]

probably not very; i'll do this.

+
+}  // namespace extensions