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

base/files/important_file_writer_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/files/important_file_writer.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 64 matching lines @@
   bool was_successful_write_observed = successful_write_observed_;
   successful_write_observed_ = false;
   return was_successful_write_observed;
 }
 
 }  // namespace
 
 class ImportantFileWriterTest : public testing::Test {
  public:
   ImportantFileWriterTest() { }
-  virtual void SetUp() {
+  void SetUp() override {
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
     file_ = temp_dir_.path().AppendASCII("test-file");
   }
 
  protected:
   SuccessfulWriteObserver successful_write_observer_;
   FilePath file_;
   MessageLoop loop_;
 
  private:
@@ skipping 90 matching lines @@
   MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       MessageLoop::QuitWhenIdleClosure(),
       TimeDelta::FromMilliseconds(100));
   MessageLoop::current()->Run();
   ASSERT_TRUE(PathExists(writer.path()));
   EXPECT_EQ("baz", GetFileContent(writer.path()));
 }
 
 }  // namespace base