Support sending KEYCODE_BACK from a VirtualDpad.

Bug: 233911853
Test: n/a
Change-Id: Ie37b3ed323a1d18cb306fd5e6d75b7fd36f084f9
diff --git a/core/java/android/hardware/input/VirtualDpad.java b/core/java/android/hardware/input/VirtualDpad.java
index 4d61553..8133472 100644
--- a/core/java/android/hardware/input/VirtualDpad.java
+++ b/core/java/android/hardware/input/VirtualDpad.java
@@ -32,8 +32,8 @@
 /**
  * A virtual dpad representing a key input mechanism on a remote device.
  *
- * This registers an InputDevice that is interpreted like a physically-connected device and
- * dispatches received events to it.
+ * <p>This registers an InputDevice that is interpreted like a physically-connected device and
+ * dispatches received events to it.</p>
  *
  * @hide
  */
@@ -44,6 +44,7 @@
             Collections.unmodifiableSet(
                     new HashSet<>(
                             Arrays.asList(
+                                    KeyEvent.KEYCODE_BACK,
                                     KeyEvent.KEYCODE_DPAD_UP,
                                     KeyEvent.KEYCODE_DPAD_DOWN,
                                     KeyEvent.KEYCODE_DPAD_LEFT,
@@ -58,8 +59,15 @@
     /**
      * Sends a key event to the system.
      *
-     * Supported key codes are KEYCODE_DPAD_UP, KEYCODE_DPAD_DOWN, KEYCODE_DPAD_LEFT,
-     * KEYCODE_DPAD_RIGHT and KEYCODE_DPAD_CENTER,
+     * <p>Supported key codes are:
+     * <ul>
+     *     <li>{@link KeyEvent.KEYCODE_DPAD_UP}</li>
+     *     <li>{@link KeyEvent.KEYCODE_DPAD_DOWN}</li>
+     *     <li>{@link KeyEvent.KEYCODE_DPAD_LEFT}</li>
+     *     <li>{@link KeyEvent.KEYCODE_DPAD_RIGHT}</li>
+     *     <li>{@link KeyEvent.KEYCODE_DPAD_CENTER}</li>
+     *     <li>{@link KeyEvent.KEYCODE_BACK}</li>
+     * </ul>
      *
      * @param event the event to send
      */