move Layer.Grid.getGridBounds function into deprecated.js

lib/deprecated.js

@@ -1805,6 +1805,30 @@ OpenLayers.Control.MouseToolbar = OpenLayers.Class(
 OpenLayers.Control.MouseToolbar.X = 6;
 OpenLayers.Control.MouseToolbar.Y = 300;
 
+/**
+ * Class: OpenLayers.Layer.Grid
+ */
+
+OpenLayers.Util.extend(OpenLayers.Layer.Grid.prototype, {
+
+    /**
+     * Method: getGridBounds
+     * Deprecated. This function will be removed in 3.0. Please use 
+     *     getTilesBounds() instead.
+     * 
+     * Returns:
+     * {<OpenLayers.Bounds>} A Bounds object representing the bounds of all the
+     * currently loaded tiles (including those partially or not at all seen 
+     * onscreen)
+     */
+    getGridBounds: function() {
+        var msg = "The getGridBounds() function is deprecated. It will be " +
+                  "removed in 3.0. Please use getTilesBounds() instead.";
+        OpenLayers.Console.warn(msg);
+        return this.getTilesBounds();
+    }
+});
+
 /**
  * Class: OpenLayers.Format.XML
  */