base: Get rid of the deprecated SysInfo::GetEnvVar.

base/sys_info.h

Index: base/sys_info.h
diff --git a/base/sys_info.h b/base/sys_info.h
index cefce132cd19e1a8d75907f9c7113b06fb7442d0..1bb4eca4de76fd61bdd0bc6954c39d6255d4784d 100644
--- a/base/sys_info.h
+++ b/base/sys_info.h
@@ -30,11 +30,6 @@ class SysInfo {
   // or -1 on failure.
   static int64 AmountOfFreeDiskSpace(const FilePath& path);
 
-  // Return the value of the given environment variable
-  // or an empty string if not defined.
-  // DEPRECATED in favor of EnvVarGetter in base/env_var.h.
-  static std::wstring GetEnvVar(const wchar_t* var);
-
   // Returns the name of the host operating system.
   static std::string OperatingSystemName();