Fix "unused variable" warnings.

chrome/renderer/plugins/chrome_plugin_placeholder.h

 // Copyright 2013 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_RENDERER_PLUGINS_CHROME_PLUGIN_PLACEHOLDER_H_
 #define CHROME_RENDERER_PLUGINS_CHROME_PLUGIN_PLACEHOLDER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 94 matching lines @@
   void OnCancelledDownloadingPlugin();
 #endif
 
   ChromeViewHostMsg_GetPluginInfo_Status status_;
 
   base::string16 title_;
 
 #if defined(ENABLE_PLUGIN_INSTALLATION)
   // |routing_id()| is the routing ID of our associated RenderView, but we have
   // a separate routing ID for messages specific to this placeholder.
-  int32_t placeholder_routing_id_;
+  int32_t placeholder_routing_id_ = MSG_ROUTING_NONE;
+
+  bool has_host_ = false;
 #endif
 
-  bool has_host_;
   int context_menu_request_id_;  // Nonzero when request pending.
   base::string16 plugin_name_;
 
   bool ignore_updates_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromePluginPlaceholder);
 };
 
 #endif  // CHROME_RENDERER_PLUGINS_CHROME_PLUGIN_PLACEHOLDER_H_