Add virtual and OVERRIDE to base/ implementation files

base/threading/non_thread_safe_unittest.cc

Index: base/threading/non_thread_safe_unittest.cc
diff --git a/base/threading/non_thread_safe_unittest.cc b/base/threading/non_thread_safe_unittest.cc
index 3236278347a885be8146bc8a5d1bf2945b2cda94..c72eec0c3c45491f695315591398f06f8e1d77fe 100644
--- a/base/threading/non_thread_safe_unittest.cc
+++ b/base/threading/non_thread_safe_unittest.cc
@@ -42,7 +42,7 @@ class CallDoStuffOnThread : public SimpleThread {
         non_thread_safe_class_(non_thread_safe_class) {
   }
 
-  virtual void Run() {
+  virtual void Run() OVERRIDE {
     non_thread_safe_class_->DoStuff();
   }
 
@@ -60,7 +60,7 @@ class DeleteNonThreadSafeClassOnThread : public SimpleThread {
         non_thread_safe_class_(non_thread_safe_class) {
   }
 
-  virtual void Run() {
+  virtual void Run() OVERRIDE {
     non_thread_safe_class_.reset();
   }