base: Add UnSetEnv function to EnvVarGetter API.

base/env_var_unittest.cc

Index: base/env_var_unittest.cc
diff --git a/base/env_var_unittest.cc b/base/env_var_unittest.cc
index d80d9975bfa7a40d48aacfc6fc67f78b0df39d75..f05a9b4d96113a2083705cd68e21fd8514445a08 100644
--- a/base/env_var_unittest.cc
+++ b/base/env_var_unittest.cc
@@ -24,9 +24,10 @@ TEST_F(EnvVarTest, HasEnvVar) {
 }
 
 TEST_F(EnvVarTest, SetEnvVar) {
+  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
+
   const char kFooUpper[] = "FOO";
   const char kFooLower[] = "foo";
-  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
   EXPECT_TRUE(env->SetEnv(kFooUpper, kFooLower));
 
   // Now verify that the environment has the new variable.
@@ -36,3 +37,21 @@ TEST_F(EnvVarTest, SetEnvVar) {
   EXPECT_TRUE(env->GetEnv(kFooUpper, &var_value));
   EXPECT_EQ(var_value, kFooLower);
 }
+
+TEST_F(EnvVarTest, UnSetEnvVar) {
+  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
+
+  const char kFooUpper[] = "FOO";
+  const char kFooLower[] = "foo";
+  // First set some environment variable.
+  EXPECT_TRUE(env->SetEnv(kFooUpper, kFooLower));
+
+  // Now verify that the environment has the new variable.
+  EXPECT_TRUE(env->HasEnv(kFooUpper));
+
+  // Finally verify that the environment variable was erased.
+  EXPECT_TRUE(env->UnSetEnv(kFooUpper));
+
+  // And check that the variable has been unset.
+  EXPECT_FALSE(env->HasEnv(kFooUpper));
+}