Revert of Standardize usage of virtual/override/final in ipc/

ipc/ipc_channel_posix_unittest.cc

Index: ipc/ipc_channel_posix_unittest.cc
diff --git a/ipc/ipc_channel_posix_unittest.cc b/ipc/ipc_channel_posix_unittest.cc
index 786623b80622102288d4217037326e83d11f752c..d5346b9b7c6b98d68063a23369642fc13be50574 100644
--- a/ipc/ipc_channel_posix_unittest.cc
+++ b/ipc/ipc_channel_posix_unittest.cc
@@ -45,35 +45,35 @@
         quit_only_on_message_(quit_only_on_message) {
   }
 
-  ~IPCChannelPosixTestListener() override {}
-
-  bool OnMessageReceived(const IPC::Message& message) override {
+  virtual ~IPCChannelPosixTestListener() {}
+
+  virtual bool OnMessageReceived(const IPC::Message& message) override {
     EXPECT_EQ(message.type(), kQuitMessage);
     status_ = MESSAGE_RECEIVED;
     QuitRunLoop();
     return true;
   }
 
-  void OnChannelConnected(int32 peer_pid) override {
+  virtual void OnChannelConnected(int32 peer_pid) override {
     status_ = CONNECTED;
     if (!quit_only_on_message_) {
       QuitRunLoop();
     }
   }
 
-  void OnChannelError() override {
+  virtual void OnChannelError() override {
     status_ = CHANNEL_ERROR;
     QuitRunLoop();
   }
 
-  void OnChannelDenied() override {
+  virtual void OnChannelDenied() override {
     status_ = DENIED;
     if (!quit_only_on_message_) {
       QuitRunLoop();
     }
   }
 
-  void OnChannelListenError() override {
+  virtual void OnChannelListenError() override {
     status_ = LISTEN_ERROR;
     if (!quit_only_on_message_) {
       QuitRunLoop();