Standardize usage of virtual/override/final specifiers in base/.

base/callback_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/callback_internal.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 48 matching lines @@
                             void(FakeInvoker, FakeInvoker)>
    FakeBindState2;
 
 class CallbackTest : public ::testing::Test {
  public:
   CallbackTest()
       : callback_a_(new FakeBindState1()),
         callback_b_(new FakeBindState2()) {
   }
 
-  virtual ~CallbackTest() {
-  }
+  ~CallbackTest() override {}
 
  protected:
   Callback<void(void)> callback_a_;
   const Callback<void(void)> callback_b_;  // Ensure APIs work with const.
   Callback<void(void)> null_callback_;
 };
 
 // Ensure we can create unbound callbacks. We need this to be able to store
 // them in class members that can be initialized later.
 TEST_F(CallbackTest, DefaultConstruction) {
@@ skipping 95 matching lines @@
 
 TEST_F(CallbackTest, CallbackHasLastRefOnContainingObject) {
   bool deleted = false;
   CallbackOwner* owner = new CallbackOwner(&deleted);
   owner->Reset();
   ASSERT_TRUE(deleted);
 }
 
 }  // namespace
 }  // namespace base