Added a new process mitigation to harden process token IL policy.

content/app/startup_helper_win.cc

Index: content/app/startup_helper_win.cc
diff --git a/content/app/startup_helper_win.cc b/content/app/startup_helper_win.cc
index ab85a43e80689794cbbd6bf232d31c4dca6b6961..e19630feb39aa2216c8b03ef8ed3a0aceb119dfe 100644
--- a/content/app/startup_helper_win.cc
+++ b/content/app/startup_helper_win.cc
@@ -43,7 +43,8 @@ void InitializeSandboxInfo(sandbox::SandboxInterfaceInfo* info) {
     // Ensure the proper mitigations are enforced for the browser process.
     sandbox::ApplyProcessMitigationsToCurrentProcess(
         sandbox::MITIGATION_DEP |
-        sandbox::MITIGATION_DEP_NO_ATL_THUNK);
+        sandbox::MITIGATION_DEP_NO_ATL_THUNK |
+        sandbox::MITIGATION_HARDEN_TOKEN_IL_POLICY);
   }
 }