Standardize usage of virtual/override/final in ui/

ui/gfx/color_analysis_unittest.cc

Index: ui/gfx/color_analysis_unittest.cc
diff --git a/ui/gfx/color_analysis_unittest.cc b/ui/gfx/color_analysis_unittest.cc
index 128209afe204937b547df76c57fc0b81e560d5ec..d65fec7bdb3995ca93d58c0a5b589270bad4d854 100644
--- a/ui/gfx/color_analysis_unittest.cc
+++ b/ui/gfx/color_analysis_unittest.cc
@@ -113,14 +113,13 @@ class MockKMeanImageSampler : public KMeanImageSampler {
         current_result_index_(0) {
   }
 
-  virtual ~MockKMeanImageSampler() {
-  }
+  ~MockKMeanImageSampler() override {}
 
   void AddSample(int sample) {
     prebaked_sample_results_.push_back(sample);
   }
 
-  virtual int GetSample(int width, int height) override {
+  int GetSample(int width, int height) override {
     if (current_result_index_ >= prebaked_sample_results_.size()) {
       current_result_index_ = 0;
     }