Add new wifi display discovery API.

The API is quite simple.  There are a few extra functions
on DisplayManager to scan, connect and disconnect from
wifi displays and get status, and a single protected
broadcast sent when the status changes.

Change-Id: Ic91dbab5ee818e790b27fa32e1a1e93788793be0
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index d0427f0..560021d 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -108,6 +108,8 @@
     <protected-broadcast
         android:name="android.bluetooth.pan.profile.action.CONNECTION_STATE_CHANGED" />
 
+    <protected-broadcast android:name="android.hardware.display.action.WIFI_DISPLAY_STATUS_CHANGED" />
+
     <protected-broadcast android:name="android.hardware.usb.action.USB_STATE" />
     <protected-broadcast android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />
     <protected-broadcast android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />