Standardize usage of virtual/override/final specifiers.

content/browser/device_monitor_udev.h

Index: content/browser/device_monitor_udev.h
diff --git a/content/browser/device_monitor_udev.h b/content/browser/device_monitor_udev.h
index a5bd5d65bf1d3907a2f6d87dd765ee98f9443a8b..4a879ef5d4d2c4c51db7f449182ca450ce97f8e5 100644
--- a/content/browser/device_monitor_udev.h
+++ b/content/browser/device_monitor_udev.h
@@ -23,13 +23,13 @@ class UdevLinux;
 class DeviceMonitorLinux : public base::MessageLoop::DestructionObserver {
  public:
   DeviceMonitorLinux();
-  virtual ~DeviceMonitorLinux();
+  ~DeviceMonitorLinux() override;
 
  private:
   // This object is deleted on the UI thread after the IO thread has been
   // destroyed. Need to know when IO thread is being destroyed so that
   // we can delete udev_.
-  virtual void WillDestroyCurrentMessageLoop() override;
+  void WillDestroyCurrentMessageLoop() override;
 
   void Initialize();
   void OnDevicesChanged(udev_device* device);