Plumb sandbox rules through the helper executable.

sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc

Index: sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc
diff --git a/sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc b/sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc
index 86ae8153e4b7e75d40fe575ca5d905cede97ac31..9d8b8b573aac9184ac12b603839f2c6f41cd6986 100644
--- a/sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc
+++ b/sandbox/mac/sandbox_mac_seatbelt_exec_unittest.cc
@@ -31,12 +31,10 @@ MULTIPROCESS_TEST_MAIN(ServerTest) {
   mac::SandboxPolicy policy;
   google::protobuf::MapPair<std::string, std::string> allowed_pair(
       "ALLOWED_READ_DIR", allowed_path);
-  google::protobuf::MapPair<std::string, std::string> exec_pair(
-      "EXECUTABLE_PATH", exec_path);
   CHECK(policy.mutable_params()->insert(allowed_pair).second);
-  CHECK(policy.mutable_params()->insert(exec_pair).second);
   policy.set_profile(profile);
 
+  CHECK(exec_server.SetParameter("EXECUTABLE_PATH", exec_path));
   CHECK(exec_server.ApplySandboxProfile(policy));
 
   // Test that the sandbox profile is actually applied.