Fix uncaught exception in WindowManager#setWallpaperOffsets (issue 5613241)

Change-Id: I4646095f4cde9514425be8ab2dbf805d9788aa5c
diff --git a/core/java/android/app/WallpaperManager.java b/core/java/android/app/WallpaperManager.java
index 91398bc..b1c1f30 100644
--- a/core/java/android/app/WallpaperManager.java
+++ b/core/java/android/app/WallpaperManager.java
@@ -635,6 +635,9 @@
                     //Log.v(TAG, "...app returning after sending offsets!");
                 } catch (RemoteException e) {
                     // Ignore.
+                } catch (IllegalArgumentException e) {
+                    // Since this is being posted, it's possible that this windowToken is no longer
+                    // valid, for example, if setWallpaperOffsets is called just before rotation.
                 }
             }
         });