NaCl: Fix Chromium style warnings in src/trusted/plugin/

ppapi/native_client/src/trusted/plugin/plugin.h

 // -*- c++ -*-
 // Copyright (c) 2012 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.
 
 // The portable representation of an instance and root scriptable object.
 // The PPAPI version of the plugin instantiates a subclass of this class.
 
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_PLUGIN_H_
 #define NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_PLUGIN_H_
@@ skipping 45 matching lines @@
 
 class Plugin : public pp::Instance {
  public:
   explicit Plugin(PP_Instance instance);
 
   // ----- Methods inherited from pp::Instance:
 
   // Initializes this plugin with <embed/object ...> tag attribute count |argc|,
   // names |argn| and values |argn|. Returns false on failure.
   // Gets called by the browser right after New().
-  virtual bool Init(uint32_t argc, const char* argn[], const char* argv[]);
+  bool Init(uint32_t argc, const char* argn[], const char* argv[]) override;
 
   // Handles document load, when the plugin is a MIME type handler.
-  virtual bool HandleDocumentLoad(const pp::URLLoader& url_loader);
+  bool HandleDocumentLoad(const pp::URLLoader& url_loader) override;
 
   // Load support.
   //
   // Starts NaCl module but does not wait until low-level
   // initialization (e.g. ld.so dynamic loading of manifest files) is
   // done.  The module will become ready later, asynchronously.  Other
   // event handlers should block until the module is ready before
   // trying to communicate with it, i.e., until nacl_ready_state is
   // DONE.
   //
@@ skipping 21 matching lines @@
 
   nacl::DescWrapperFactory* wrapper_factory() const { return wrapper_factory_; }
 
   const PPB_NaCl_Private* nacl_interface() const { return nacl_interface_; }
   pp::UMAPrivate& uma_interface() { return uma_interface_; }
 
  private:
   NACL_DISALLOW_COPY_AND_ASSIGN(Plugin);
   // The browser will invoke the destructor via the pp::Instance
   // pointer to this object, not from base's Delete().
-  ~Plugin();
+  ~Plugin() override;
 
   // Shuts down socket connection, service runtime, and receive thread,
   // in this order, for the main nacl subprocess.
   void ShutDownSubprocesses();
 
   // Histogram helper functions, internal to Plugin so they can use
   // uma_interface_ normally.
   void HistogramTimeSmall(const std::string& name, int64_t ms);
 
   // Loads and starts a helper (e.g. llc, ld) NaCl module.
@@ skipping 56 matching lines @@
 
   PP_NaClFileInfo nexe_file_info_;
 
   const PPB_NaCl_Private* nacl_interface_;
   pp::UMAPrivate uma_interface_;
 };
 
 }  // namespace plugin
 
 #endif  // NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_PLUGIN_H_