Add UiUtilities.getViewOrNull()

They're variants of getView() that will *not* crash even if the view
doesn't exist.

I didn't add them before as they would be exactly same as findViewbyId(),
but now that we make use of generics they'll be handy.

Change-Id: Ib649e591a987183064c7e98afe0e2414d9e62280

src/com/android/email/activity/UiUtilities.java

@@ -66,6 +66,18 @@ public class UiUtilities {
         }
     }
 
+    /** Generics version of {@link Activity#findViewById} */
+    @SuppressWarnings("unchecked")
+    public static <T extends View> T getViewOrNull(Activity parent, int viewId) {
+        return (T) parent.findViewById(viewId);
+    }
+
+    /** Generics version of {@link View#findViewById} */
+    @SuppressWarnings("unchecked")
+    public static <T extends View> T getViewOrNull(View parent, int viewId) {
+        return (T) parent.findViewById(viewId);
+    }
+
     /**
      * Same as {@link Activity#findViewById}, but crashes if there's no view.
      */