Coverity: Pass values by reference.

chrome/browser/ui/gtk/location_bar_view_gtk.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_GTK_LOCATION_BAR_VIEW_GTK_H_
 #define CHROME_BROWSER_UI_GTK_LOCATION_BAR_VIEW_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 210 matching lines @@
 
     void set_preview_enabled(bool preview_enabled) {
       preview_enabled_ = preview_enabled;
     }
 
     bool IsVisible() { return GTK_WIDGET_VISIBLE(widget()); }
 
     // Called to notify the PageAction that it should determine whether to be
     // visible or hidden. |contents| is the TabContents that is active, |url|
     // is the current page URL.
-    void UpdateVisibility(TabContents* contents, GURL url);
+    void UpdateVisibility(TabContents* contents, const GURL& url);
 
     // A callback from ImageLoadingTracker for when the image has loaded.
     virtual void OnImageLoaded(
         SkBitmap* image, const ExtensionResource& resource, int index);
 
     // Simulate left mouse click on the page action button.
     void TestActivatePageAction();
 
     // Overridden from ExtensionContextMenuModel::PopupDelegate:
     virtual void InspectPopup(ExtensionAction* action);
@@ skipping 204 matching lines @@
   // Indicate if |tab_to_search_hint_| should be shown.
   bool show_keyword_hint_;
 
   // The last search keyword that was shown via the |tab_to_search_box_|.
   string16 last_keyword_;
 
   DISALLOW_COPY_AND_ASSIGN(LocationBarViewGtk);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_LOCATION_BAR_VIEW_GTK_H_