Add missing (and remove superfluous) 'explicit' from constructors.

webkit/glue/webmenuitem.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 WEBMENUITEM_H_
 #define WEBMENUITEM_H_
 
 #include <vector>
 
 #include "base/string16.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebMenuItemInfo.h"
 #include "webkit/glue/webkit_glue_export.h"
 
 // Container for information about entries in an HTML select popup menu and
 // custom entries of the context menu.
 struct WEBKIT_GLUE_EXPORT WebMenuItem {
   enum Type {
     OPTION    = WebKit::WebMenuItemInfo::Option,
     CHECKABLE_OPTION = WebKit::WebMenuItemInfo::CheckableOption,
     GROUP     = WebKit::WebMenuItemInfo::Group,
     SEPARATOR = WebKit::WebMenuItemInfo::Separator,
     SUBMENU  // This is currently only used by Pepper, not by WebKit.
   };
 
   WebMenuItem();
-  WebMenuItem(const WebKit::WebMenuItemInfo& item);
+  explicit WebMenuItem(const WebKit::WebMenuItemInfo& item);
   WebMenuItem(const WebMenuItem& item);
   ~WebMenuItem();
 
   string16 label;
   string16 toolTip;
   Type type;
   unsigned action;
   bool rtl;
   bool has_directional_override;
   bool enabled;
   bool checked;
   std::vector<WebMenuItem> submenu;
 };
 
 #endif  // WEBMENUITEM_H_