Update {virtual,override} to follow C++11 style in chrome.

chrome/browser/ui/webui/profiler_ui.cc

Index: chrome/browser/ui/webui/profiler_ui.cc
diff --git a/chrome/browser/ui/webui/profiler_ui.cc b/chrome/browser/ui/webui/profiler_ui.cc
index a16c05f1e08aa201d5978c023dc86a058a555592..aff5b41bca12c230159285db250936883cbd2be7 100644
--- a/chrome/browser/ui/webui/profiler_ui.cc
+++ b/chrome/browser/ui/webui/profiler_ui.cc
@@ -53,17 +53,17 @@ class ProfilerWebUIDataSource : public content::URLDataSource {
 
  protected:
   // content::URLDataSource implementation.
-  virtual std::string GetSource() override {
+  std::string GetSource() override {
     return chrome::kChromeUIProfilerHost;
   }
 
-  virtual std::string GetMimeType(const std::string& path) const override {
+  std::string GetMimeType(const std::string& path) const override {
     if (EndsWith(path, ".js", false))
       return "application/javascript";
     return "text/html";
   }
 
-  virtual void StartDataRequest(
+  void StartDataRequest(
       const std::string& path,
       bool is_incognito,
       const content::URLDataSource::GotDataCallback& callback) override {