Standardize usage of virtual/override/final in ipc/

ipc/ipc_test_sink.h

Index: ipc/ipc_test_sink.h
diff --git a/ipc/ipc_test_sink.h b/ipc/ipc_test_sink.h
index 13386f107d999d20a151ea5537aa9213c77b1e04..75e582db6828295cf47ae99d108e170919396730 100644
--- a/ipc/ipc_test_sink.h
+++ b/ipc/ipc_test_sink.h
@@ -73,19 +73,19 @@ class Message;
 class TestSink : public Channel {
  public:
   TestSink();
-  virtual ~TestSink();
+  ~TestSink() override;
 
   // Interface in IPC::Channel. This copies the message to the sink and then
   // deletes it.
-  virtual bool Send(IPC::Message* message) override;
-  virtual bool Connect() override WARN_UNUSED_RESULT;
-  virtual void Close() override;
-  virtual base::ProcessId GetPeerPID() const override;
-  virtual base::ProcessId GetSelfPID() const override;
+  bool Send(IPC::Message* message) override;
+  bool Connect() override WARN_UNUSED_RESULT;
+  void Close() override;
+  base::ProcessId GetPeerPID() const override;
+  base::ProcessId GetSelfPID() const override;
 
 #if defined(OS_POSIX) && !defined(OS_NACL)
-  virtual int GetClientFileDescriptor() const override;
-  virtual base::ScopedFD TakeClientFileDescriptor() override;
+  int GetClientFileDescriptor() const override;
+  base::ScopedFD TakeClientFileDescriptor() override;
 #endif  // defined(OS_POSIX) && !defined(OS_NACL)
 
   // Used by the source of the messages to send the message to the sink. This