Standardize usage of virtual/override/final specifiers.

components/nacl/loader/nonsfi/nonsfi_main.cc

Index: components/nacl/loader/nonsfi/nonsfi_main.cc
diff --git a/components/nacl/loader/nonsfi/nonsfi_main.cc b/components/nacl/loader/nonsfi/nonsfi_main.cc
index c053586fe54fdc0a5e89faba37546fc8c5f603e9..f452a49ec94453cb076b7b57a6db23daa7ddc3b8 100644
--- a/components/nacl/loader/nonsfi/nonsfi_main.cc
+++ b/components/nacl/loader/nonsfi/nonsfi_main.cc
@@ -28,10 +28,9 @@ class PluginMainDelegate : public base::PlatformThread::Delegate {
       : entry_point_(entry_point) {
   }
 
-  virtual ~PluginMainDelegate() {
-  }
+  ~PluginMainDelegate() override {}
 
-  virtual void ThreadMain() override {
+  void ThreadMain() override {
     base::PlatformThread::SetName("NaClMainThread");
 
     // This will only happen once per process, so we give the permission to