Interface for GetFeatureInfo

When a source implements this interface, the layer renderer can
access the source to get feature info.

src/ol/renderer/layerrenderer.js

@@ -73,6 +73,26 @@ ol.renderer.Layer = function(mapRenderer, layer) {
 goog.inherits(ol.renderer.Layer, goog.Disposable);
 
 
+/**
+ * @param {ol.Pixel} pixel Pixel coordinate relative to the map viewport.
+ * @param {function(string, ol.layer.Layer)} success Callback for
+ *     successful queries. The passed arguments are the resulting feature
+ *     information and the layer.
+ * @param {function()=} opt_error Callback for unsuccessful queries.
+ */
+ol.renderer.Layer.prototype.getFeatureInfoForPixel =
+    function(pixel, success, opt_error) {
+  var layer = this.getLayer();
+  var source = layer.getSource();
+  if (goog.isFunction(source.getFeatureInfoForPixel)) {
+    var callback = function(layerFeatureInfo) {
+      success(layerFeatureInfo, layer);
+    };
+    source.getFeatureInfoForPixel(pixel, this.getMap(), callback, opt_error);
+  }
+};
+
+
 /**
  * @protected
  * @return {ol.layer.Layer} Layer.

src/ol/source/featureinfosource.js

@@ -0,0 +1,18 @@
+goog.provide('ol.source.FeatureInfoSource');
+
+
+
+/**
+ * @interface
+ */
+ol.source.FeatureInfoSource = function() {};
+
+
+/**
+ * @param {ol.Pixel} pixel Pixel.
+ * @param {ol.Map} map The map that the pixel belongs to.
+ * @param {function(string)} success Callback with feature info.
+ * @param {function()=} opt_error Optional error callback.
+ */
+ol.source.FeatureInfoSource.prototype.getFeatureInfoForPixel =
+    goog.abstractMethod;