Update {virtual,override,final} to follow C++11 style in chrome/browser/chromeos/drive.

The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.

This patch was automatically generated with a ChromeOS build using a
variation of https://codereview.chromium.org/598073004.

BUG=417463
[email protected]

Review URL: https://codereview.chromium.org/817063006

Cr-Commit-Position: refs/heads/master@{#312655}
diff --git a/chrome/browser/chromeos/drive/file_cache_unittest.cc b/chrome/browser/chromeos/drive/file_cache_unittest.cc
index 10c0baf..4d02999 100644
--- a/chrome/browser/chromeos/drive/file_cache_unittest.cc
+++ b/chrome/browser/chromeos/drive/file_cache_unittest.cc
@@ -33,7 +33,7 @@
 // Tests FileCache methods working with the blocking task runner.
 class FileCacheTest : public testing::Test {
  protected:
-  virtual void SetUp() override {
+  void SetUp() override {
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
     const base::FilePath metadata_dir = temp_dir_.path().AppendASCII("meta");
     cache_files_dir_ = temp_dir_.path().AppendASCII(kCacheFileDirectory);