Move empty listner to KeyboardActionListener.Adapter

Change-Id: Ic7bad73c089de015746c667bbfb2c09bd429a9fc
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardActionListener.java b/java/src/com/android/inputmethod/keyboard/KeyboardActionListener.java
index c76acd1..60d09d6 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardActionListener.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardActionListener.java
@@ -94,6 +94,8 @@
     public boolean onCustomRequest(int requestCode);
 
     public static class Adapter implements KeyboardActionListener {
+        public static final Adapter EMPTY_LISTENER = new Adapter();
+
         @Override
         public void onPressKey(int primaryCode) {}
         @Override
diff --git a/java/src/com/android/inputmethod/keyboard/PointerTracker.java b/java/src/com/android/inputmethod/keyboard/PointerTracker.java
index c1b148d..0556fdd 100644
--- a/java/src/com/android/inputmethod/keyboard/PointerTracker.java
+++ b/java/src/com/android/inputmethod/keyboard/PointerTracker.java
@@ -176,7 +176,7 @@
     private DrawingProxy mDrawingProxy;
     private TimerProxy mTimerProxy;
     private KeyDetector mKeyDetector;
-    private KeyboardActionListener mListener = EMPTY_LISTENER;
+    private KeyboardActionListener mListener = KeyboardActionListener.Adapter.EMPTY_LISTENER;
 
     private Keyboard mKeyboard;
     private int mPhantonSuddenMoveThreshold;
@@ -333,10 +333,6 @@
     // true if a sliding key input is allowed.
     private boolean mIsAllowedSlidingKeyInput;
 
-    // Empty {@link KeyboardActionListener}
-    private static final KeyboardActionListener EMPTY_LISTENER =
-            new KeyboardActionListener.Adapter();
-
     private final GestureStrokeWithPreviewPoints mGestureStrokeWithPreviewPoints;
 
     public static void init(final boolean needsPhantomSuddenMoveEventHack) {