base: Add UnSetEnv function to EnvVarGetter API.

base/env_var.h

 // Copyright (c) 2010 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.
 
 #ifndef BASE_ENV_VAR_H_
 #define BASE_ENV_VAR_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 
 namespace base {
 
 namespace env_vars {
 
 #if defined(OS_POSIX)
 extern const char kHome[];
 #endif
 
 }  // namespace env_vars
 
-// These are used to derive mocks for unittests.
 class EnvVarGetter {
  public:
   virtual ~EnvVarGetter();
 
+  // Static factory method that returns the implementation that provide the
+  // appropriate platform-specific instance.
+  static EnvVarGetter* Create();
+
   // Gets an environment variable's value and stores it in |result|.
   // Returns false if the key is unset.
   virtual bool GetEnv(const char* variable_name, std::string* result) = 0;
 
   // Syntactic sugar for GetEnv(variable_name, NULL);
   virtual bool HasEnv(const char* variable_name);
 
   // Returns true on success, otherwise returns false.
   virtual bool SetEnv(const char* variable_name,
                       const std::string& new_value) = 0;
 
-  // Create an instance of EnvVarGetter
-  static EnvVarGetter* Create();
+  // Returns true on success, otherwise returns false.
+  virtual bool UnSetEnv(const char* variable_name) = 0;

[viettrungluu, 2010/08/03 06:02:13]

Even more after-the-fact drive-by nit: "unset" is a single word, so it should be
"UnsetEnv" (no capital 'S').

 };
 
 }  // namespace base
 
 #endif  // BASE_ENV_VAR_H_