Update {virtual,override} to follow C++11 style in ppapi.

ppapi/proxy/network_monitor_resource.h

Index: ppapi/proxy/network_monitor_resource.h
diff --git a/ppapi/proxy/network_monitor_resource.h b/ppapi/proxy/network_monitor_resource.h
index 529dd6e1e39d8880d9dd4f39d70da8cdf887cd96..e63ae390fa746807fa2fb4c13713e469a1ae380b 100644
--- a/ppapi/proxy/network_monitor_resource.h
+++ b/ppapi/proxy/network_monitor_resource.h
@@ -24,15 +24,15 @@ class NetworkMonitorResource : public PluginResource,
  public:
   explicit NetworkMonitorResource(Connection connection,
                                   PP_Instance instance);
-  virtual ~NetworkMonitorResource();
+  ~NetworkMonitorResource() override;
 
   // PluginResource overrides.
   ppapi::thunk::PPB_NetworkMonitor_API* AsPPB_NetworkMonitor_API() override;
-  virtual void OnReplyReceived(const ResourceMessageReplyParams& params,
-                               const IPC::Message& msg) override;
+  void OnReplyReceived(const ResourceMessageReplyParams& params,
+                       const IPC::Message& msg) override;
 
   // thunk::PPB_NetworkMonitor_API interface
-  virtual int32_t UpdateNetworkList(
+  int32_t UpdateNetworkList(
       PP_Resource* network_list,
       scoped_refptr<TrackedCallback> callback) override;