Standardize usage of virtual/override/final specifiers.

media/ffmpeg/ffmpeg_common_unittest.cc

 // Copyright (c) 2011 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/logging.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 #include "media/filters/ffmpeg_glue.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media {
 
 class FFmpegCommonTest : public testing::Test {
  public:
   FFmpegCommonTest() { FFmpegGlue::InitializeFFmpeg(); }
-  virtual ~FFmpegCommonTest() {};
+  ~FFmpegCommonTest() override{};
 };
 
 TEST_F(FFmpegCommonTest, OpusAudioDecoderConfig) {
   AVCodecContext context = {0};
   context.codec_type = AVMEDIA_TYPE_AUDIO;
   context.codec_id = AV_CODEC_ID_OPUS;
   context.channel_layout = CHANNEL_LAYOUT_STEREO;
   context.channels = 2;
   context.sample_fmt = AV_SAMPLE_FMT_FLT;
 
@@ skipping 92 matching lines @@
   for (size_t i = 0; i < arraysize(invalid_date_strings); ++i) {
     const char* date_string = invalid_date_strings[i];
     base::Time result;
     EXPECT_FALSE(FFmpegUTCDateToTime(date_string, &result))
         << "date_string '" << date_string << "'";
     EXPECT_TRUE(result.is_null());
   }
 }
 
 }  // namespace media