Clear environment variables for nacl_helper

base/process/launch.h

Index: base/process/launch.h
diff --git a/base/process/launch.h b/base/process/launch.h
index 9e39fba6297d92bfcaae23dd89b439c187e99156..2ee173e54fbccd009a2a7fc12bb271210b7e73f9 100644
--- a/base/process/launch.h
+++ b/base/process/launch.h
@@ -88,10 +88,15 @@ struct BASE_EXPORT LaunchOptions {
   // job if any.
   bool force_breakaway_from_job_;
 #else
-  // Set/unset environment variables. Empty (the default) means to inherit
-  // the same environment. See AlterEnvironment().
+  // Set/unset environment variables. These are applied on top of the parent
+  // process environment.  Empty (the default) means to inherit the same
+  // environment. See AlterEnvironment().
   EnvironmentMap environ;
 
+  // Clear the environment for the new process before processing changes from
+  // |environ|.
+  bool clear_environ;
+
   // If non-null, remap file descriptors according to the mapping of
   // src fd->dest fd to propagate FDs into the child process.
   // This pointer is owned by the caller and must live through the