Standardize usage of virtual/override/final in chrome/

chrome/test/base/tracing.cc

Index: chrome/test/base/tracing.cc
diff --git a/chrome/test/base/tracing.cc b/chrome/test/base/tracing.cc
index 8a37ab99948f666d06ba0624bd0eaf8f462cdbd6..6ed0f54a316b92f4a72e9aa2f30b842f93e6a4be 100644
--- a/chrome/test/base/tracing.cc
+++ b/chrome/test/base/tracing.cc
@@ -24,18 +24,18 @@ class StringTraceSink : public content::TracingController::TraceDataSink {
   StringTraceSink(std::string* result, const base::Closure& callback)
       : result_(result), completion_callback_(callback) {}
 
-  virtual void AddTraceChunk(const std::string& chunk) override {
+  void AddTraceChunk(const std::string& chunk) override {
     *result_ += result_->empty() ? "[" : ",";
     *result_ += chunk;
   }
-  virtual void Close() override {
+  void Close() override {
     if (!result_->empty())
       *result_ += "]";
     completion_callback_.Run();
   }
 
  private:
-  virtual ~StringTraceSink() {}
+  ~StringTraceSink() override {}
 
   std::string* result_;
   base::Closure completion_callback_;