Reland: cros: Show notification when low-power charger connected

ash/system/chromeos/power/tray_power.h

Index: ash/system/chromeos/power/tray_power.h
diff --git a/ash/system/chromeos/power/tray_power.h b/ash/system/chromeos/power/tray_power.h
index db33f350d5d9014feb96aeb03e1d3d1044b3fa5c..7e193c3f0170250bb86c7bca8d3f926d88b2295b 100644
--- a/ash/system/chromeos/power/tray_power.h
+++ b/ash/system/chromeos/power/tray_power.h
@@ -11,9 +11,14 @@
 class SkBitmap;
 
 namespace gfx {
+class Image;
 class ImageSkia;
 }
 
+namespace message_center {
+class MessageCenter;
+}
+
 namespace ash {
 namespace internal {
 
@@ -27,10 +32,22 @@ enum IconSet {
   ICON_DARK
 };
 
-class TrayPower : public SystemTrayItem,
-                  public chromeos::PowerManagerHandler::Observer {
+class ASH_EXPORT TrayPower : public SystemTrayItem,
+                             public chromeos::PowerManagerHandler::Observer {
  public:
-  explicit TrayPower(SystemTray* system_tray);
+  // Visible for testing.
+  enum NotificationState {
+    NOTIFICATION_NONE,
+
+    // Low battery charge.
+    NOTIFICATION_LOW_POWER,
+
+    // Critically low battery charge.
+    NOTIFICATION_CRITICAL,
+  };
+
+  TrayPower(SystemTray* system_tray,
+            message_center::MessageCenter* message_center);
   virtual ~TrayPower();
 
   // Gets whether battery charging is unreliable for |supply_status|.
@@ -58,6 +75,9 @@ class TrayPower : public SystemTrayItem,
                                         bool charging_unreliable,
                                         IconSet icon_set);
 
+  // Returns an icon for the USB charger notification.
+  static gfx::Image GetUsbChargerNotificationImage();
+
   // Gets the battery accessible string for |supply_status|.
   static base::string16 GetAccessibleNameString(
       const chromeos::PowerSupplyStatus& supply_status);
@@ -66,11 +86,7 @@ class TrayPower : public SystemTrayItem,
   static int GetRoundedBatteryPercentage(double battery_percentage);
 
  private:
-  enum NotificationState {
-    NOTIFICATION_NONE,
-    NOTIFICATION_LOW_POWER,
-    NOTIFICATION_CRITICAL
-  };
+  friend class TrayPowerTest;
 
   // Overridden from SystemTrayItem.
   virtual views::View* CreateTrayView(user::LoginStatus status) OVERRIDE;
@@ -91,16 +107,26 @@ class TrayPower : public SystemTrayItem,
   // Requests a power status update.
   void RequestStatusUpdate() const;
 
+  // Show a notification that a low-power USB charger has been connected.
+  // Returns true if a notification was shown or explicitly hidden.
+  bool MaybeShowUsbChargerNotification(
+      const chromeos::PowerSupplyStatus& old_status,
+      const chromeos::PowerSupplyStatus& new_status);
+
   // Sets |notification_state_|. Returns true if a notification should be shown.
   bool UpdateNotificationState(const chromeos::PowerSupplyStatus& status);
   bool UpdateNotificationStateForRemainingTime(int remaining_seconds);
   bool UpdateNotificationStateForRemainingPercentage(
       double remaining_percentage);
 
+  message_center::MessageCenter* message_center_;  // Not owned.
   tray::PowerTrayView* power_tray_;
   tray::PowerNotificationView* notification_view_;
   NotificationState notification_state_;
 
+  // Power supply status at the last update.
+  chromeos::PowerSupplyStatus last_power_supply_status_;
+
   DISALLOW_COPY_AND_ASSIGN(TrayPower);
 };