Use Launcher.getLauncher(Context) instead of type-casting.

Bug: 32010039
Change-Id: Icb80d3e547a706740b84df2cb80f99e4a7f81c43
diff --git a/src/com/android/launcher3/CellLayout.java b/src/com/android/launcher3/CellLayout.java
index 6714d9f..57fd0e7 100644
--- a/src/com/android/launcher3/CellLayout.java
+++ b/src/com/android/launcher3/CellLayout.java
@@ -196,7 +196,7 @@
         // the user where a dragged item will land when dropped.
         setWillNotDraw(false);
         setClipToPadding(false);
-        mLauncher = (Launcher) context;
+        mLauncher = Launcher.getLauncher(context);
 
         DeviceProfile grid = mLauncher.getDeviceProfile();