Add virtual and OVERRIDE to base/ implementation files

base/message_pump_libevent_unittest.cc

Index: base/message_pump_libevent_unittest.cc
diff --git a/base/message_pump_libevent_unittest.cc b/base/message_pump_libevent_unittest.cc
index c3ec97e3a3fc0c6e5d4cf7aee1a93b3fef2fdfc6..5532abad28abae1065d7b3ed3f94db709747ea39 100644
--- a/base/message_pump_libevent_unittest.cc
+++ b/base/message_pump_libevent_unittest.cc
@@ -55,8 +55,8 @@ class StupidWatcher : public MessagePumpLibevent::Watcher {
   virtual ~StupidWatcher() {}
 
   // base:MessagePumpLibevent::Watcher interface
-  virtual void OnFileCanReadWithoutBlocking(int fd) {}
-  virtual void OnFileCanWriteWithoutBlocking(int fd) {}
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE {}
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE {}
 };
 
 #if GTEST_HAS_DEATH_TEST && !defined(NDEBUG)
@@ -85,10 +85,10 @@ class DeleteWatcher : public MessagePumpLibevent::Watcher {
   virtual ~DeleteWatcher() {}
 
   // base:MessagePumpLibevent::Watcher interface
-  virtual void OnFileCanReadWithoutBlocking(int /* fd */) {
+  virtual void OnFileCanReadWithoutBlocking(int /* fd */) OVERRIDE {
     NOTREACHED();
   }
-  virtual void OnFileCanWriteWithoutBlocking(int /* fd */) {
+  virtual void OnFileCanWriteWithoutBlocking(int /* fd */) OVERRIDE {
     delete controller_;
   }
 
@@ -118,10 +118,10 @@ class StopWatcher : public MessagePumpLibevent::Watcher {
   virtual ~StopWatcher() {}
 
   // base:MessagePumpLibevent::Watcher interface
-  virtual void OnFileCanReadWithoutBlocking(int /* fd */) {
+  virtual void OnFileCanReadWithoutBlocking(int /* fd */) OVERRIDE {
     NOTREACHED();
   }
-  virtual void OnFileCanWriteWithoutBlocking(int /* fd */) {
+  virtual void OnFileCanWriteWithoutBlocking(int /* fd */) OVERRIDE {
     controller_->StopWatchingFileDescriptor();
   }