intents: Change default_service_url() to return a const-ref.

chrome/browser/ui/intents/web_intent_picker_model.h

Index: chrome/browser/ui/intents/web_intent_picker_model.h
diff --git a/chrome/browser/ui/intents/web_intent_picker_model.h b/chrome/browser/ui/intents/web_intent_picker_model.h
index d3fcaf18b557dfa60f7176ccfe36fbea89c795f3..fb535c2253e33f4c37ae0caa3a8e28b1261f63f4 100644
--- a/chrome/browser/ui/intents/web_intent_picker_model.h
+++ b/chrome/browser/ui/intents/web_intent_picker_model.h
@@ -76,7 +76,7 @@ class WebIntentPickerModel {
   const string16& type() const { return type_; }
   void set_type(const string16& type) { type_ = type; }
 
-  GURL default_service_url() const { return default_service_url_; }
+  const GURL& default_service_url() const { return default_service_url_; }
   void set_default_service_url(const GURL& default_url) {
     default_service_url_ = default_url;
   }