Standardize usage of virtual/override/final specifiers.

chrome/browser/download/download_query_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 <string>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 27 matching lines @@
 bool AlwaysReturn(bool result, const DownloadItem& item) {
   return result;
 }
 
 }  // anonymous namespace
 
 class DownloadQueryTest : public testing::Test {
  public:
   DownloadQueryTest() {}
 
-  virtual ~DownloadQueryTest() {}
+  ~DownloadQueryTest() override {}
 
-  virtual void TearDown() {
-    STLDeleteElements(&mocks_);
-  }
+  void TearDown() override { STLDeleteElements(&mocks_); }
 
   void CreateMocks(int count) {
     for (int i = 0; i < count; ++i) {
       mocks_.push_back(new content::MockDownloadItem());
       EXPECT_CALL(mock(mocks_.size() - 1), GetId()).WillRepeatedly(Return(
           mocks_.size() - 1));
     }
   }
 
   content::MockDownloadItem& mock(int index) { return *mocks_[index]; }
@@ skipping 542 matching lines @@
   base::Time start = base::Time::Now();
   Search();
   base::Time end = base::Time::Now();
   double nanos = (end - start).InMillisecondsF() * 1000.0 * 1000.0;
   double nanos_per_item = nanos / static_cast<double>(kNumItems);
   double nanos_per_item_per_filter = nanos_per_item
     / static_cast<double>(kNumFilters);
   std::cout << "Search took " << nanos_per_item_per_filter
             << " nanoseconds per item per filter.\n";
 }