Standardize usage of virtual/override/final specifiers.

ui/app_list/search/mixer_unittest.cc

 // Copyright 2013 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/memory/scoped_vector.h"
 #include "base/strings/string16.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 64 matching lines @@
  private:
   std::string prefix_;
   size_t count_;
 
   DISALLOW_COPY_AND_ASSIGN(TestSearchProvider);
 };
 
 class MixerTest : public testing::Test {
  public:
   MixerTest() {}
-  virtual ~MixerTest() {}
+  ~MixerTest() override {}
 
   // testing::Test overrides:
-  virtual void SetUp() override {
+  void SetUp() override {
     results_.reset(new AppListModel::SearchResults);
 
     providers_.push_back(new TestSearchProvider("app"));
     providers_.push_back(new TestSearchProvider("omnibox"));
     providers_.push_back(new TestSearchProvider("webstore"));
     providers_.push_back(new TestSearchProvider("people"));
 
     mixer_.reset(new Mixer(results_.get()));
     mixer_->Init();
     mixer_->AddProviderToGroup(Mixer::MAIN_GROUP, providers_[0]);
@@ skipping 174 matching lines @@
   EXPECT_EQ(old_ui_result_ids[0],
             TestSearchResult::GetInstanceId(ui_results.GetItemAt(3)));
   EXPECT_EQ(old_ui_result_ids[1],
             TestSearchResult::GetInstanceId(ui_results.GetItemAt(0)));
   EXPECT_EQ(old_ui_result_ids[2],
             TestSearchResult::GetInstanceId(ui_results.GetItemAt(2)));
 }
 
 }  // namespace test
 }  // namespace app_list