SystemGestures: Only send touch events to gesture detector.

The gesture detector does only accept touch events, not other
pointer events. This causes unnecessary warnings in logcat.

BUG=b/26388796
TEST=Use mouse, no more warnings in logs.

Change-Id: Ibc98f5101d95d588562164707dc0e6953e25e794
(cherry picked from commit ac3a4c478a6aa37be002de19789b5700f1d6e4c4)
diff --git a/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java b/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java
index b06fe58..80e4341 100644
--- a/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java
+++ b/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java
@@ -89,7 +89,7 @@
 
     @Override
     public void onPointerEvent(MotionEvent event) {
-        if (mGestureDetector != null) {
+        if (mGestureDetector != null && event.isTouchEvent()) {
             mGestureDetector.onTouchEvent(event);
         }
         switch (event.getActionMasked()) {