Introduce stem keycodes for Wear

This change adds four new stem keycodes for Android Wear. These
keycodes are intended to represent the various hardware buttons
around the watch.  There is one primary stem key that will be used
for power/settings and three generic stem keys that will be
customizable.

BUG: 21903503
Change-Id: I8835cfdba3a8819aae61b47d018c0794ba5f772e
diff --git a/core/java/android/view/KeyEvent.java b/core/java/android/view/KeyEvent.java
index f6ce353..75e6229 100644
--- a/core/java/android/view/KeyEvent.java
+++ b/core/java/android/view/KeyEvent.java
@@ -761,8 +761,17 @@
      * Backs out one level of a navigation hierarchy or collapses the item that currently has 
      * focus. */
     public static final int KEYCODE_NAVIGATE_OUT    = 263;
+    /** Key code constant: Primary stem key for Wear
+     * Main power/reset button on watch. */
+    public static final int KEYCODE_STEM_PRIMARY = 264;
+    /** Key code constant: Generic stem key 1 for Wear */
+    public static final int KEYCODE_STEM_1 = 265;
+    /** Key code constant: Generic stem key 2 for Wear */
+    public static final int KEYCODE_STEM_2 = 266;
+    /** Key code constant: Generic stem key 3 for Wear */
+    public static final int KEYCODE_STEM_3 = 267;
 
-    private static final int LAST_KEYCODE = KEYCODE_NAVIGATE_OUT;
+    private static final int LAST_KEYCODE = KEYCODE_STEM_3;
 
     // NOTE: If you add a new keycode here you must also add it to:
     //  isSystem()