Show a notification when dual-role devices are connected.

The notification informs the user whether a connected dual-role
device is being used as a power source, or which dual-role devices
this device is charging. It has minimal priority (doesn't toast). It
opens the power settings when clicked.

When the device is using a dedicated charger, the notification
doesn't appear (because we don't override dedicated chargers).

1-pager: https://docs.google.com/document/d/1UPYK_VIhtcBTZgyjfe4ogszqtOdVqmSOXxUTQ28GpJQ/edit#

To test, use chrome://device-emulator in Debug builds.

BUG=547260

Review URL: https://codereview.chromium.org/1515493004

Cr-Commit-Position: refs/heads/master@{#365345}

11 files changed, 358 insertions, 2 deletions

diff --git a/ash/ash.gyp b/ash/ash.gyp
index 1dd7430..f6201bd 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -326,6 +326,8 @@
       'system/chromeos/network/vpn_list_view.h',
       'system/chromeos/power/battery_notification.cc',
       'system/chromeos/power/battery_notification.h',
+      'system/chromeos/power/dual_role_notification.cc',
+      'system/chromeos/power/dual_role_notification.h',
       'system/chromeos/power/power_event_observer.cc',
       'system/chromeos/power/power_event_observer.h',
       'system/chromeos/power/power_status.cc',
diff --git a/ash/ash_chromeos_strings.grdp b/ash/ash_chromeos_strings.grdp
index 639c698..ce7e6e4 100644
--- a/ash/ash_chromeos_strings.grdp
+++ b/ash/ash_chromeos_strings.grdp
@@ -30,6 +30,18 @@
   <message name="IDS_ASH_STATUS_TRAY_LOW_POWER_CHARGER_MESSAGE_SHORT" desc="The message body of a notification indicating that a low-current USB charger has been connected, short version.">
     Your <ph name="DEVICE_TYPE">$1<ex>Chromebook</ex></ph> may not charge while it is turned on.
   </message>
+  <message name="IDS_ASH_STATUS_TRAY_CHARGING_FROM_DUAL_ROLE_TITLE" desc="The message title of a notification indicating that the device is being charged by a connected dual-role USB Type-C device.">
+    Charging from <ph name="POWER_SOURCE">$1<ex>USB-C device (left port)</ex></ph>
+  </message>
+  <message name="IDS_ASH_STATUS_TRAY_CHARGING_DUAL_ROLE_DEVICE_TITLE" desc="The message title of a notification indicating that the device is charging the connected USB Type-C device.">
+    Charging <ph name="POWER_SOURCE">$1<ex>USB-C device (left port)</ex></ph>
+  </message>
+  <message name="IDS_ASH_STATUS_TRAY_CHARGING_DUAL_ROLE_DEVICES_TITLE" desc="The message title of a notification indicating that the device is charging multiple connected USB Type-C devices.">
+    Charging connected USB-C devices
+  </message>
+  <message name="IDS_ASH_STATUS_TRAY_DUAL_ROLE_MESSAGE" desc="The message body of a notification, which indicates that the user can click the notification to see and change which device is being used as a power source.">
+    Click for more options
+  </message>
   <message name="IDS_ASH_POWER_SOURCE_PORT_LEFT" desc="The text identifying an external device, when that device is connected to the USB Type-C port on the left side of this device.">
     USB-C device (left port)
   </message>
diff --git a/ash/system/chromeos/power/dual_role_notification.cc b/ash/system/chromeos/power/dual_role_notification.cc
new file mode 100644
index 0000000..0c5cda0
--- /dev/null
+++ b/ash/system/chromeos/power/dual_role_notification.cc
@@ -0,0 +1,157 @@
+// Copyright 2015 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/chromeos/power/dual_role_notification.h"
+
+#include <set>
+
+#include "ash/shell.h"
+#include "ash/system/chromeos/power/power_status.h"
+#include "ash/system/system_notifier.h"
+#include "ash/system/tray/system_tray_delegate.h"
+#include "base/strings/utf_string_conversions.h"
+#include "grit/ash_resources.h"
+#include "grit/ash_strings.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/base/l10n/time_format.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/image/image.h"
+#include "ui/message_center/message_center.h"
+#include "ui/message_center/notification.h"
+#include "ui/message_center/notification_delegate.h"
+
+using message_center::MessageCenter;
+using message_center::Notification;
+
+namespace ash {
+namespace {
+
+const char kDualRoleNotificationId[] = "dual-role";
+
+// Opens power settings on click.
+class DualRoleNotificationDelegate
+    : public message_center::NotificationDelegate {
+ public:
+  DualRoleNotificationDelegate() {}
+
+  // Overridden from message_center::NotificationDelegate.
+  void Click() override {
+    Shell::GetInstance()->system_tray_delegate()->ShowPowerSettings();
+  }
+
+ private:
+  ~DualRoleNotificationDelegate() override {}
+
+  DISALLOW_COPY_AND_ASSIGN(DualRoleNotificationDelegate);
+};
+
+}  // namespace
+
+DualRoleNotification::DualRoleNotification(MessageCenter* message_center)
+    : message_center_(message_center),
+      num_dual_role_sinks_(0),
+      line_power_connected_(false) {}
+
+DualRoleNotification::~DualRoleNotification() {
+  if (message_center_->FindVisibleNotificationById(kDualRoleNotificationId))
+    message_center_->RemoveNotification(kDualRoleNotificationId, false);
+}
+
+void DualRoleNotification::Update() {
+  const PowerStatus& status = *PowerStatus::Get();
+  DCHECK(status.HasDualRoleDevices());
+
+  std::string current_power_source_id = status.GetCurrentPowerSourceID();
+
+  scoped_ptr<PowerStatus::PowerSource> new_source;
+  scoped_ptr<PowerStatus::PowerSource> new_sink;
+  size_t num_sinks_found = 0;
+  for (const auto& source : status.GetPowerSources()) {
+    // The power source can't be changed if there's a dedicated charger.
+    if (source.type == PowerStatus::DEDICATED_CHARGER) {
+      dual_role_source_.reset();
+      line_power_connected_ = true;
+      if (message_center_->FindVisibleNotificationById(kDualRoleNotificationId))
+        message_center_->RemoveNotification(kDualRoleNotificationId, false);
+      return;
+    }
+
+    if (source.id == current_power_source_id) {
+      new_source.reset(new PowerStatus::PowerSource(source));
+      continue;
+    }
+    num_sinks_found++;
+    // The notification only shows the sink port if it is the only sink.
+    if (num_sinks_found == 1)
+      new_sink.reset(new PowerStatus::PowerSource(source));
+    else
+      new_sink.reset();
+  }
+
+  // Check if the notification should change.
+  bool change = false;
+  if (PowerStatus::Get()->IsLinePowerConnected() != line_power_connected_) {
+    change = true;
+    line_power_connected_ = PowerStatus::Get()->IsLinePowerConnected();
+  } else if (new_source && dual_role_source_) {
+    if (new_source->description_id != dual_role_source_->description_id)
+      change = true;
+  } else if (new_source || dual_role_source_) {
+    change = true;
+  } else {
+    // Notification differs for 0, 1, and 2+ sinks.
+    if ((num_sinks_found < num_dual_role_sinks_ && num_sinks_found < 2) ||
+        (num_sinks_found > num_dual_role_sinks_ && num_dual_role_sinks_ < 2)) {
+      change = true;
+    } else if (num_sinks_found == 1) {
+      // The description matters if there's only one dual-role device.
+      change = new_sink->description_id != dual_role_sink_->description_id;
+    }
+  }
+
+  dual_role_source_ = std::move(new_source);
+  dual_role_sink_ = std::move(new_sink);
+  num_dual_role_sinks_ = num_sinks_found;
+
+  if (!change)
+    return;
+
+  if (!message_center_->FindVisibleNotificationById(kDualRoleNotificationId)) {
+    message_center_->AddNotification(CreateNotification());
+  } else {
+    message_center_->UpdateNotification(kDualRoleNotificationId,
+                                        CreateNotification());
+  }
+}
+
+scoped_ptr<Notification> DualRoleNotification::CreateNotification() {
+  base::string16 title;
+  if (dual_role_source_) {
+    title = l10n_util::GetStringFUTF16(
+        IDS_ASH_STATUS_TRAY_CHARGING_FROM_DUAL_ROLE_TITLE,
+        l10n_util::GetStringUTF16(dual_role_source_->description_id));
+  } else if (num_dual_role_sinks_ == 1) {
+    title = l10n_util::GetStringFUTF16(
+        IDS_ASH_STATUS_TRAY_CHARGING_DUAL_ROLE_DEVICE_TITLE,
+        l10n_util::GetStringUTF16(dual_role_sink_->description_id));
+  } else {
+    title = l10n_util::GetStringUTF16(
+        IDS_ASH_STATUS_TRAY_CHARGING_DUAL_ROLE_DEVICES_TITLE);
+  }
+
+  scoped_ptr<Notification> notification(new Notification(
+      message_center::NOTIFICATION_TYPE_SIMPLE, kDualRoleNotificationId, title,
+      l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_DUAL_ROLE_MESSAGE),
+      ui::ResourceBundle::GetSharedInstance().GetImageNamed(
+          IDR_AURA_NOTIFICATION_LOW_POWER_CHARGER),
+      base::string16(), GURL(),
+      message_center::NotifierId(message_center::NotifierId::SYSTEM_COMPONENT,
+                                 system_notifier::kNotifierDualRole),
+      message_center::RichNotificationData(),
+      new DualRoleNotificationDelegate));
+  notification->set_priority(message_center::MIN_PRIORITY);
+  return notification;
+}
+
+}  // namespace ash
diff --git a/ash/system/chromeos/power/dual_role_notification.h b/ash/system/chromeos/power/dual_role_notification.h
new file mode 100644
index 0000000..d49ec08
--- /dev/null
+++ b/ash/system/chromeos/power/dual_role_notification.h
@@ -0,0 +1,44 @@
+// Copyright 2015 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.
+
+#ifndef ASH_SYSTEM_CHROMEOS_POWER_DUAL_ROLE_NOTIFICATION_H_
+#define ASH_SYSTEM_CHROMEOS_POWER_DUAL_ROLE_NOTIFICATION_H_
+
+#include "ash/ash_export.h"
+#include "ash/system/chromeos/power/power_status.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace message_center {
+class MessageCenter;
+class Notification;
+}
+
+namespace ash {
+
+// Shows a non-toasting MessageCenter notification based on what dual-role
+// devices are connected.
+class ASH_EXPORT DualRoleNotification {
+ public:
+  explicit DualRoleNotification(message_center::MessageCenter* message_center);
+  ~DualRoleNotification();
+
+  // Creates or updates the notification.
+  void Update();
+
+ private:
+  // Creates the notification using the updated status.
+  scoped_ptr<message_center::Notification> CreateNotification();
+
+  message_center::MessageCenter* message_center_;
+  scoped_ptr<PowerStatus::PowerSource> dual_role_source_;
+  scoped_ptr<PowerStatus::PowerSource> dual_role_sink_;
+  size_t num_dual_role_sinks_;
+  bool line_power_connected_;
+
+  DISALLOW_COPY_AND_ASSIGN(DualRoleNotification);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_CHROMEOS_POWER_DUAL_ROLE_NOTIFICATION_H_
diff --git a/ash/system/chromeos/power/tray_power.cc b/ash/system/chromeos/power/tray_power.cc
index 1ca6dc7..a23b52a 100644
--- a/ash/system/chromeos/power/tray_power.cc
+++ b/ash/system/chromeos/power/tray_power.cc
@@ -9,6 +9,7 @@
 #include "ash/shell.h"
 #include "ash/system/chromeos/devicetype_utils.h"
 #include "ash/system/chromeos/power/battery_notification.h"
+#include "ash/system/chromeos/power/dual_role_notification.h"
 #include "ash/system/date/date_view.h"
 #include "ash/system/system_notifier.h"
 #include "ash/system/tray/system_tray_delegate.h"
@@ -190,6 +191,7 @@ void TrayPower::OnPowerStatusChanged() {
     return;
 
   MaybeShowUsbChargerNotification();
+  MaybeShowDualRoleNotification();
 
   if (battery_alert) {
     // Remove any existing notification so it's dismissed before adding a new
@@ -241,6 +243,18 @@ bool TrayPower::MaybeShowUsbChargerNotification() {
   return false;
 }
 
+void TrayPower::MaybeShowDualRoleNotification() {
+  const PowerStatus& status = *PowerStatus::Get();
+  if (!status.HasDualRoleDevices()) {
+    dual_role_notification_.reset();
+    return;
+  }
+
+  if (!dual_role_notification_)
+    dual_role_notification_.reset(new DualRoleNotification(message_center_));
+  dual_role_notification_->Update();
+}
+
 bool TrayPower::UpdateNotificationState() {
   const PowerStatus& status = *PowerStatus::Get();
   if (!status.IsBatteryPresent() ||
diff --git a/ash/system/chromeos/power/tray_power.h b/ash/system/chromeos/power/tray_power.h
index d88bb29..2c84658 100644
--- a/ash/system/chromeos/power/tray_power.h
+++ b/ash/system/chromeos/power/tray_power.h
@@ -22,6 +22,7 @@ class MessageCenter;
 namespace ash {
 
 class BatteryNotification;
+class DualRoleNotification;
 
 namespace tray {
 class PowerTrayView;
@@ -83,10 +84,13 @@ class ASH_EXPORT TrayPower : public SystemTrayItem,
   // Overridden from PowerStatus::Observer.
   void OnPowerStatusChanged() override;
 
-  // Show a notification that a low-power USB charger has been connected.
+  // Shows a notification that a low-power USB charger has been connected.
   // Returns true if a notification was shown or explicitly hidden.
   bool MaybeShowUsbChargerNotification();
 
+  // Shows a notification when dual-role devices are connected.
+  void MaybeShowDualRoleNotification();
+
   // Sets |notification_state_|. Returns true if a notification should be shown.
   bool UpdateNotificationState();
   bool UpdateNotificationStateForRemainingTime();
@@ -95,6 +99,7 @@ class ASH_EXPORT TrayPower : public SystemTrayItem,
   message_center::MessageCenter* message_center_;  // Not owned.
   tray::PowerTrayView* power_tray_;
   scoped_ptr<BatteryNotification> battery_notification_;
+  scoped_ptr<DualRoleNotification> dual_role_notification_;
   NotificationState notification_state_;
 
   // Was a USB charger connected the last time OnPowerStatusChanged() was
diff --git a/ash/system/chromeos/power/tray_power_unittest.cc b/ash/system/chromeos/power/tray_power_unittest.cc
index d0b9705..352cae5 100644
--- a/ash/system/chromeos/power/tray_power_unittest.cc
+++ b/ash/system/chromeos/power/tray_power_unittest.cc
@@ -20,11 +20,12 @@ namespace {
 
 class MockMessageCenter : public message_center::FakeMessageCenter {
  public:
-  MockMessageCenter() : add_count_(0), remove_count_(0) {}
+  MockMessageCenter() : add_count_(0), remove_count_(0), update_count_(0) {}
   ~MockMessageCenter() override {}
 
   int add_count() const { return add_count_; }
   int remove_count() const { return remove_count_; }
+  int update_count() const { return update_count_; }
 
   // message_center::FakeMessageCenter overrides:
   void AddNotification(scoped_ptr<Notification> notification) override {
@@ -39,6 +40,15 @@ class MockMessageCenter : public message_center::FakeMessageCenter {
     remove_count_++;
     notifications_.erase(id);
   }
+  void UpdateNotification(const std::string& id,
+                          scoped_ptr<Notification> new_notification) override {
+    update_count_++;
+    Notification* notification = FindVisibleNotificationById(id);
+    if (notification)
+      notifications_.erase(id);
+    notifications_.insert(
+        std::make_pair(new_notification->id(), std::move(new_notification)));
+  }
 
   Notification* FindVisibleNotificationById(const std::string& id) override {
     auto it = notifications_.find(id);
@@ -48,6 +58,7 @@ class MockMessageCenter : public message_center::FakeMessageCenter {
  private:
   int add_count_;
   int remove_count_;
+  int update_count_;
   std::map<std::string, scoped_ptr<Notification>> notifications_;
 
   DISALLOW_COPY_AND_ASSIGN(MockMessageCenter);
@@ -87,6 +98,11 @@ class TrayPowerTest : public test::AshTestBase {
     return tray_power_->MaybeShowUsbChargerNotification();
   }
 
+  void MaybeShowDualRoleNotification(const PowerSupplyProperties& proto) {
+    PowerStatus::Get()->SetProtoForTesting(proto);
+    tray_power_->MaybeShowDualRoleNotification();
+  }
+
   void UpdateNotificationState(const PowerSupplyProperties& proto,
                                TrayPower::NotificationState expected_state,
                                bool expected_add,
@@ -199,6 +215,105 @@ TEST_F(TrayPowerTest, MaybeShowUsbChargerNotification) {
   SetUsbChargerConnected(true);
 }
 
+TEST_F(TrayPowerTest, MaybeShowDualRoleNotification) {
+  PowerSupplyProperties discharging = DefaultPowerSupplyProperties();
+  discharging.set_supports_dual_role_devices(true);
+  MaybeShowDualRoleNotification(discharging);
+  EXPECT_EQ(0, message_center()->add_count());
+  EXPECT_EQ(0, message_center()->update_count());
+  EXPECT_EQ(0, message_center()->remove_count());
+
+  // Notification shows when connecting a dual-role device.
+  PowerSupplyProperties dual_role = DefaultPowerSupplyProperties();
+  dual_role.set_supports_dual_role_devices(true);
+  power_manager::PowerSupplyProperties_PowerSource* source =
+      dual_role.add_available_external_power_source();
+  source->set_id("dual-role1");
+  source->set_active_by_default(false);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(1, message_center()->add_count());
+  EXPECT_EQ(0, message_center()->update_count());
+  EXPECT_EQ(0, message_center()->remove_count());
+
+  // Connecting another dual-role device updates the notification to be plural.
+  source = dual_role.add_available_external_power_source();
+  source->set_id("dual-role2");
+  source->set_active_by_default(false);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(1, message_center()->add_count());
+  EXPECT_EQ(1, message_center()->update_count());
+  EXPECT_EQ(0, message_center()->remove_count());
+
+  // Connecting a 3rd dual-role device doesn't affect the notification.
+  source = dual_role.add_available_external_power_source();
+  source->set_id("dual-role3");
+  source->set_active_by_default(false);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(1, message_center()->add_count());
+  EXPECT_EQ(1, message_center()->update_count());
+  EXPECT_EQ(0, message_center()->remove_count());
+
+  // Connecting a legacy USB device removes the notification.
+  PowerSupplyProperties legacy(dual_role);
+  power_manager::PowerSupplyProperties_PowerSource* legacy_source =
+      legacy.add_available_external_power_source();
+  legacy_source->set_id("legacy");
+  legacy_source->set_active_by_default(true);
+  legacy.set_external_power_source_id("legacy");
+  legacy.set_external_power(
+      power_manager::PowerSupplyProperties_ExternalPower_USB);
+  MaybeShowDualRoleNotification(legacy);
+  EXPECT_EQ(1, message_center()->add_count());
+  EXPECT_EQ(1, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // Removing the legacy USB device adds the notification again.
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(1, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // Charging from the device updates the notification.
+  dual_role.set_external_power_source_id("dual-role1");
+  dual_role.set_external_power(
+      power_manager::PowerSupplyProperties_ExternalPower_USB);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(2, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // Adding a device as a sink doesn't change the notification, because the
+  // notification exposes the source.
+  source = dual_role.add_available_external_power_source();
+  source->set_active_by_default(false);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(2, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // Changing the source to a sink changes the notification.
+  dual_role.set_external_power_source_id("");
+  dual_role.set_external_power(
+      power_manager::PowerSupplyProperties_ExternalPower_DISCONNECTED);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(3, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // An unrelated change has no effect.
+  dual_role.set_battery_time_to_empty_sec(2 * 60 * 60);
+  MaybeShowDualRoleNotification(dual_role);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(3, message_center()->update_count());
+  EXPECT_EQ(1, message_center()->remove_count());
+
+  // Removing devices hides the notification.
+  MaybeShowDualRoleNotification(discharging);
+  EXPECT_EQ(2, message_center()->add_count());
+  EXPECT_EQ(3, message_center()->update_count());
+  EXPECT_EQ(2, message_center()->remove_count());
+}
+
 TEST_F(TrayPowerTest, UpdateNotificationState) {
   // No notifications when no battery present.
   PowerSupplyProperties no_battery = DefaultPowerSupplyProperties();
diff --git a/ash/system/system_notifier.cc b/ash/system/system_notifier.cc
index 8356a59..808d78c 100644
--- a/ash/system/system_notifier.cc
+++ b/ash/system/system_notifier.cc
@@ -75,6 +75,7 @@ const char kNotifierDeprecatedAccelerator[] = "ash.accelerator-controller";
 const char kNotifierDisplay[] = "ash.display";
 const char kNotifierDisplayError[] = "ash.display.error";
 const char kNotifierDisplayResolutionChange[] = "ash.display.resolution-change";
+const char kNotifierDualRole[] = "ash.dual-role";
 const char kNotifierLocale[] = "ash.locale";
 const char kNotifierMultiProfileFirstRun[] = "ash.multi-profile.first-run";
 const char kNotifierNetworkPortalDetector[] = "ash.network.portal-detector";
diff --git a/ash/system/system_notifier.h b/ash/system/system_notifier.h
index 95bac2f..64ad280 100644
--- a/ash/system/system_notifier.h
+++ b/ash/system/system_notifier.h
@@ -20,6 +20,7 @@ ASH_EXPORT extern const char kNotifierDeprecatedAccelerator[];
 ASH_EXPORT extern const char kNotifierDisplay[];
 ASH_EXPORT extern const char kNotifierDisplayResolutionChange[];
 ASH_EXPORT extern const char kNotifierDisplayError[];
+ASH_EXPORT extern const char kNotifierDualRole[];
 ASH_EXPORT extern const char kNotifierLocale[];
 ASH_EXPORT extern const char kNotifierMultiProfileFirstRun[];
 ASH_EXPORT extern const char kNotifierNetwork[];
diff --git a/ash/system/tray/system_tray_delegate.cc b/ash/system/tray/system_tray_delegate.cc
index a5d49b5..fe081c0 100644
--- a/ash/system/tray/system_tray_delegate.cc
+++ b/ash/system/tray/system_tray_delegate.cc
@@ -124,6 +124,8 @@ void SystemTrayDelegate::ShowNetworkSettingsForGuid(const std::string& guid) {
 void SystemTrayDelegate::ShowDisplaySettings() {
 }
 
+void SystemTrayDelegate::ShowPowerSettings() {}
+
 void SystemTrayDelegate::ShowChromeSlow() {
 }
 
diff --git a/ash/system/tray/system_tray_delegate.h b/ash/system/tray/system_tray_delegate.h
index 3f84f4b..1d2e0c2 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -188,6 +188,9 @@ class ASH_EXPORT SystemTrayDelegate {
   // Shows settings related to multiple displays.
   virtual void ShowDisplaySettings();
 
+  // Shows settings related to power.
+  virtual void ShowPowerSettings();
+
   // Shows the page that lets you disable performance tracing.
   virtual void ShowChromeSlow();