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

base/debug/stack_trace_posix.cc

Index: base/debug/stack_trace_posix.cc
diff --git a/base/debug/stack_trace_posix.cc b/base/debug/stack_trace_posix.cc
index 9e477cfbb7c14044e682dc3f2298c94813463078..137b4ecc8de959f44ed6e6a92600f2480689805e 100644
--- a/base/debug/stack_trace_posix.cc
+++ b/base/debug/stack_trace_posix.cc
@@ -402,7 +402,7 @@ 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);
@@ -417,9 +417,7 @@ class StreamBacktraceOutputHandler : public BacktraceOutputHandler {
   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_;