Add virtual and OVERRIDE to base/ implementation files

base/threading/sequenced_worker_pool_unittest.cc

Index: base/threading/sequenced_worker_pool_unittest.cc
diff --git a/base/threading/sequenced_worker_pool_unittest.cc b/base/threading/sequenced_worker_pool_unittest.cc
index 1c29c345833cd9bfd31117799dee4ed28b1e1ed1..2becd0993c031025a25562dd8094cc61936419f7 100644
--- a/base/threading/sequenced_worker_pool_unittest.cc
+++ b/base/threading/sequenced_worker_pool_unittest.cc
@@ -152,11 +152,11 @@ class SequencedWorkerPoolTest : public testing::Test {
       : pool_owner_(kNumWorkerThreads, "test"),
         tracker_(new TestTracker) {}
 
-  ~SequencedWorkerPoolTest() {}
+  virtual ~SequencedWorkerPoolTest() {}
 
-  virtual void SetUp() {}
+  virtual void SetUp() OVERRIDE {}
 
-  virtual void TearDown() {
+  virtual void TearDown() OVERRIDE {
     pool()->Shutdown();
   }