add wireless charger support

bug: 6879638

- add new enum value BATTERY_PLUGGED_WIRELESS
- check for sys online file with contents "Wireless"

Change-Id: I22dc3c40f50573c98643e7b5cbcb237d0216530d
diff --git a/core/java/android/os/BatteryStats.java b/core/java/android/os/BatteryStats.java
index fcc0ae4..54f2fe3 100644
--- a/core/java/android/os/BatteryStats.java
+++ b/core/java/android/os/BatteryStats.java
@@ -2071,6 +2071,9 @@
                         case BatteryManager.BATTERY_PLUGGED_USB:
                             pw.print("usb");
                             break;
+                        case BatteryManager.BATTERY_PLUGGED_WIRELESS:
+                            pw.print("wireless");
+                            break;
                         default:
                             pw.print(oldPlug);
                             break;