Standardize usage of virtual/override/final in remoting/

remoting/host/clipboard_mac.mm

Index: remoting/host/clipboard_mac.mm
diff --git a/remoting/host/clipboard_mac.mm b/remoting/host/clipboard_mac.mm
index b4988a6c1eeac00f5c8c3fdb69387bededf791b9..48ce8525d6103a7622eb8299c2486d65a4de283a 100644
--- a/remoting/host/clipboard_mac.mm
+++ b/remoting/host/clipboard_mac.mm
@@ -28,14 +28,12 @@ namespace remoting {
 class ClipboardMac : public Clipboard {
  public:
   ClipboardMac();
-  virtual ~ClipboardMac();
+  ~ClipboardMac() override;
 
   // Must be called on the UI thread.
-  virtual void Start(
-      scoped_ptr<protocol::ClipboardStub> client_clipboard) override;
-  virtual void InjectClipboardEvent(
-      const protocol::ClipboardEvent& event) override;
-  virtual void Stop() override;
+  void Start(scoped_ptr<protocol::ClipboardStub> client_clipboard) override;
+  void InjectClipboardEvent(const protocol::ClipboardEvent& event) override;
+  void Stop() override;
 
  private:
   void CheckClipboardForChanges();