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

base/environment.cc

Index: base/environment.cc
diff --git a/base/environment.cc b/base/environment.cc
index c5477305a1fa7ace523aadc9a46a5408e6559cd1..6cf7a18cbb704d7072c74edf6a0ca52d7da3a988 100644
--- a/base/environment.cc
+++ b/base/environment.cc
@@ -22,8 +22,7 @@ namespace {
 
 class EnvironmentImpl : public base::Environment {
  public:
-  virtual bool GetVar(const char* variable_name,
-                      std::string* result) OVERRIDE {
+  bool GetVar(const char* variable_name, std::string* result) override {
     if (GetVarImpl(variable_name, result))
       return true;
 
@@ -42,12 +41,12 @@ class EnvironmentImpl : public base::Environment {
     return GetVarImpl(alternate_case_var.c_str(), result);
   }
 
-  virtual bool SetVar(const char* variable_name,
-                      const std::string& new_value) OVERRIDE {
+  bool SetVar(const char* variable_name,
+              const std::string& new_value) override {
     return SetVarImpl(variable_name, new_value);
   }
 
-  virtual bool UnSetVar(const char* variable_name) OVERRIDE {
+  bool UnSetVar(const char* variable_name) override {
     return UnSetVarImpl(variable_name);
   }