Adding MSDL feedback to dragging apps and widgest over drop targets.

The ButtonDropTarget class delivers MSDL feedback onDragEnter.

Test: DeleteDropTargetTest
Test: manual. Verified haptics when dragging apps and widgtes over
  "Remove" and secondary drop areas.
Flag: com.android.launcher3.msdl_feedback
Bug: 371249457
Bug: 371315650
Change-Id: Ic3f79ab5e3da7bb26797f2a1bfb79b5e37b3ac97

src/com/android/launcher3/ButtonDropTarget.java

@@ -41,8 +41,11 @@ import com.android.launcher3.dragndrop.DragLayer;
 import com.android.launcher3.dragndrop.DragOptions;
 import com.android.launcher3.dragndrop.DragView;
 import com.android.launcher3.model.data.ItemInfo;
+import com.android.launcher3.util.MSDLPlayerWrapper;
 import com.android.launcher3.views.ActivityContext;
 
+import com.google.android.msdl.data.model.MSDLToken;
+
 /**
  * Implements a DropTarget.
  */
@@ -62,6 +65,7 @@ public abstract class ButtonDropTarget extends TextView
     protected final ActivityContext mActivityContext;
     protected final DropTargetHandler mDropTargetHandler;
     protected DropTargetBar mDropTargetBar;
+    private final MSDLPlayerWrapper mMSDLPlayerWrapper;
 
     /** Whether this drop target is active for the current drag */
     protected boolean mActive;
@@ -94,6 +98,7 @@ public abstract class ButtonDropTarget extends TextView
         super(context, attrs, defStyle);
         mActivityContext = ActivityContext.lookupContext(context);
         mDropTargetHandler = mActivityContext.getDropTargetHandler();
+        mMSDLPlayerWrapper = MSDLPlayerWrapper.INSTANCE.get(context);
 
         Resources resources = getResources();
         mDragDistanceThreshold = resources.getDimensionPixelSize(R.dimen.drag_distanceThreshold);
@@ -142,6 +147,10 @@ public abstract class ButtonDropTarget extends TextView
 
     @Override
     public final void onDragEnter(DragObject d) {
+        // Perform Haptic feedback
+        if (Flags.msdlFeedback()) {
+            mMSDLPlayerWrapper.playToken(MSDLToken.SWIPE_THRESHOLD_INDICATOR);
+        }
         if (!mAccessibleDrag && !mTextVisible) {
             // Show tooltip
             hideTooltip();