Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 22831)
+++ wp-includes/functions.php	(working copy)
@@ -2273,8 +2273,11 @@
  * @param mixed $response Variable (usually an array or object) to encode as JSON, then print and die.
  */
 function wp_send_json( $response ) {
+	nocache_headers();
 	@header( 'Content-Type: application/json; charset=' . get_option( 'blog_charset' ) );
+
 	echo json_encode( $response );
+
 	if ( defined( 'DOING_AJAX' ) && DOING_AJAX )
 		wp_die();
 	else
Index: wp-includes/js/media-models.js
===================================================================
--- wp-includes/js/media-models.js	(revision 22831)
+++ wp-includes/js/media-models.js	(working copy)
@@ -789,4 +789,9 @@
 		}
 	});
 
-}(jQuery));
\ No newline at end of file
+	// Clean up. Prevents mobile browsers caching
+	$(window).on('unload', function(){
+		window.wp = null;
+	});
+
+}(jQuery));