Flip the left/right speaker when the device is in yoga mode.

ash/system/audio/tray_audio.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 "ash/system/audio/tray_audio.h"
 
 #include <cmath>
 
 #include "ash/ash_constants.h"
+#include "ash/display/display_manager.h"
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/shell.h"
 #include "ash/system/audio/tray_audio_delegate.h"
 #include "ash/system/audio/volume_view.h"
 #include "ash/system/tray/actionable_view.h"
 #include "ash/system/tray/fixed_sized_scroll_view.h"
 #include "ash/system/tray/hover_highlight_view.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/volume_control_delegate.h"
 #include "base/strings/utf_string_conversions.h"
 #include "grit/ash_resources.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/display.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia_operations.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/controls/slider.h"
 #include "ui/views/layout/box_layout.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
 TrayAudio::TrayAudio(SystemTray* system_tray,
                      scoped_ptr<system::TrayAudioDelegate> audio_delegate)
     : TrayImageItem(system_tray, IDR_AURA_UBER_TRAY_VOLUME_MUTE),
       audio_delegate_(audio_delegate.Pass()),
       volume_view_(NULL),
       pop_up_volume_view_(false) {
   Shell::GetInstance()->system_tray_notifier()->AddAudioObserver(this);
+  Shell::GetScreen()->AddObserver(this);
 }
 
 TrayAudio::~TrayAudio() {
+  Shell::GetScreen()->RemoveObserver(this);
   Shell::GetInstance()->system_tray_notifier()->RemoveAudioObserver(this);
 }
 
 // static
 bool TrayAudio::ShowAudioDeviceMenu() {
 #if defined(OS_CHROMEOS)
   return true;
 #else
   return false;
 #endif
@@ skipping 65 matching lines @@
 }
 
 void TrayAudio::OnActiveOutputNodeChanged() {
   Update();
 }
 
 void TrayAudio::OnActiveInputNodeChanged() {
   Update();
 }
 
+void TrayAudio::OnDisplayAdded(const gfx::Display& new_display) {
+  if (new_display.id() != gfx::Display::InternalDisplayId())
+    return;
+  ChangeInternalSpeakerChannelMode();
+}
+
+void TrayAudio::OnDisplayRemoved(const gfx::Display& old_display) {
+  if (old_display.id() != gfx::Display::InternalDisplayId())
+    return;
+  ChangeInternalSpeakerChannelMode();
+}
+
+void TrayAudio::OnDisplayMetricsChanged(const gfx::Display& display,
+                                        uint32_t changed_metrics) {
+  if (display.id() != gfx::Display::InternalDisplayId())
+    return;
+
+  if (changed_metrics & gfx::DisplayObserver::DISPLAY_METRIC_ROTATION)
+    ChangeInternalSpeakerChannelMode();
+}
+
+void TrayAudio::ChangeInternalSpeakerChannelMode() {
+  // Swap left/right channel only if it is in Yoga mode.
+  system::TrayAudioDelegate::AudioChannelMode channel_mode =
+      system::TrayAudioDelegate::NORMAL;
+  if (gfx::Display::InternalDisplayId() != gfx::Display::kInvalidDisplayID) {
+    const DisplayInfo& display_info =
+        Shell::GetInstance()->display_manager()->GetDisplayInfo(
+            gfx::Display::InternalDisplayId());
+    if (display_info.rotation() == gfx::Display::ROTATE_180)
+      channel_mode = system::TrayAudioDelegate::LEFT_RIGHT_SWAPPED;
+  }
+
+  audio_delegate_->SetInternalSpeakerChannelMode(channel_mode);

[flackr, 2014/10/02 00:39:19]

This feels a little misplaced since it doesn't have anything to do with the tray
control and I think it will fire twice if you have two shelves (i.e. two
displays). Ideally I think we would have a separate controller which just
listens to display added/removed/changed and only flips channels.

+}
+
 void TrayAudio::Update() {
   if (tray_view())
       tray_view()->SetVisible(GetInitialVisibility());
   if (volume_view_) {
     volume_view_->SetVolumeLevel(
         static_cast<float>(audio_delegate_->GetOutputVolumeLevel()) / 100.0f);
     volume_view_->Update();
   }
 }
 
 }  // namespace ash