replace 'virtual ... OVERRIDE' with '... override'

base/debug/stack_trace_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/debug/stack_trace.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdio.h>
@@ skipping 384 matching lines @@
   write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
 #endif  // ARCH_CPU_32_BITS
 #endif  // defined(OS_MACOSX)
   _exit(1);
 }
 
 class PrintBacktraceOutputHandler : public BacktraceOutputHandler {
  public:
   PrintBacktraceOutputHandler() {}
 
-  virtual void HandleOutput(const char* output) OVERRIDE {
+  void HandleOutput(const char* output) override {
     // NOTE: This code MUST be async-signal safe (it's used by in-process
     // stack dumping signal handler). NO malloc or stdio is allowed here.
     PrintToStderr(output);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PrintBacktraceOutputHandler);
 };
 
 class StreamBacktraceOutputHandler : public BacktraceOutputHandler {
  public:
   explicit StreamBacktraceOutputHandler(std::ostream* os) : os_(os) {
   }
 
-  virtual void HandleOutput(const char* output) OVERRIDE {
-    (*os_) << output;
-  }
+  void HandleOutput(const char* output) override { (*os_) << output; }
 
  private:
   std::ostream* os_;
 
   DISALLOW_COPY_AND_ASSIGN(StreamBacktraceOutputHandler);
 };
 
 void WarmUpBacktrace() {
   // Warm up stack trace infrastructure. It turns out that on the first
   // call glibc initializes some internal data structures using pthread_once,
@@ skipping 393 matching lines @@
     *ptr = *start;
     *start++ = ch;
   }
   return buf;
 }
 
 }  // namespace internal
 
 }  // namespace debug
 }  // namespace base