Standardize usage of virtual/override/final specifiers.

remoting/host/clipboard_x11.cc

Index: remoting/host/clipboard_x11.cc
diff --git a/remoting/host/clipboard_x11.cc b/remoting/host/clipboard_x11.cc
index dea67057d47ec27e93a7026c17b7adfbfc5cf4cf..fa046391b396b2060e7fdf969cbcb9008f111f6a 100644
--- a/remoting/host/clipboard_x11.cc
+++ b/remoting/host/clipboard_x11.cc
@@ -20,18 +20,16 @@ class ClipboardX11 : public Clipboard,
                      public base::MessageLoopForIO::Watcher {
  public:
   ClipboardX11();
-  virtual ~ClipboardX11();
+  ~ClipboardX11() override;
 
   // Clipboard interface.
-  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;
 
   // MessageLoopForIO::Watcher interface.
-  virtual void OnFileCanReadWithoutBlocking(int fd) override;
-  virtual void OnFileCanWriteWithoutBlocking(int fd) override;
+  void OnFileCanReadWithoutBlocking(int fd) override;
+  void OnFileCanWriteWithoutBlocking(int fd) override;
 
  private:
   void OnClipboardChanged(const std::string& mime_type,