Make launcher implement PageSwitchListener.

Change-Id: Ief4b0cb4700aeace56a3c923a0a669a626c6506b
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index ea2da30..c614942 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -96,6 +96,7 @@
 import android.widget.Toast;
 
 import com.android.launcher3.DropTarget.DragObject;
+import com.android.launcher3.PagedView.PageSwitchListener;
 
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
@@ -119,7 +120,7 @@
  */
 public class Launcher extends Activity
         implements View.OnClickListener, OnLongClickListener, LauncherModel.Callbacks,
-                   View.OnTouchListener {
+                   View.OnTouchListener, PageSwitchListener {
     static final String TAG = "Launcher";
     static final boolean LOGD = false;
 
@@ -1230,6 +1231,7 @@
         mLauncherView = findViewById(R.id.launcher);
         mDragLayer = (DragLayer) findViewById(R.id.drag_layer);
         mWorkspace = (Workspace) mDragLayer.findViewById(R.id.workspace);
+        mWorkspace.setPageSwitchListener(this);
         mPageIndicators = mDragLayer.findViewById(R.id.page_indicator);
 
         mLauncherView.setSystemUiVisibility(
@@ -4450,6 +4452,10 @@
         mWorkspace.beginDragShared(dragView, source);
     }
 
+    @Override
+    public void onPageSwitch(View newPage, int newPageIndex) {
+    }
+
     /**
      * Prints out out state for debugging.
      */