Reset mPointerIconShape properly on window manager.

Sometimes mPointerIconShape wrongly remember old icon shape,
so that it fails to specify the icon on some situation, such
as reported in the bug.
- task == null: happening tasks are overlapping and mouse moves
  directly from an edge of a task to inside of another task
- hover_exit: happening the mouse moves outside of any tasks.
  I believe I added this line but anyways it's been lost at
  some point.

Bug: 26011155
Change-Id: I0bdc345a28089bd13443d9b7b8e7c770e56247f3
diff --git a/services/core/java/com/android/server/wm/TaskTapPointerEventListener.java b/services/core/java/com/android/server/wm/TaskTapPointerEventListener.java
index 2f890be..af109d4 100644
--- a/services/core/java/com/android/server/wm/TaskTapPointerEventListener.java
+++ b/services/core/java/com/android/server/wm/TaskTapPointerEventListener.java
@@ -109,6 +109,7 @@
                 final int y = (int) motionEvent.getY();
                 final Task task = mDisplayContent.findTaskForControlPoint(x, y);
                 if (task == null) {
+                    mPointerIconShape = STYLE_NOT_SPECIFIED;
                     break;
                 }
                 task.getDimBounds(mTmpRect);
@@ -137,6 +138,7 @@
             } break;
 
             case MotionEvent.ACTION_HOVER_EXIT:
+                mPointerIconShape = STYLE_NOT_SPECIFIED;
                 motionEvent.getDevice().setPointerShape(STYLE_DEFAULT);
                 break;