Allow the MITIGATION_WIN32K_DISABLE process mitigation to be set in the renderer sandbox.

sandbox/win/src/process_mitigations.cc

Index: sandbox/win/src/process_mitigations.cc
diff --git a/sandbox/win/src/process_mitigations.cc b/sandbox/win/src/process_mitigations.cc
index 0775b2d5ff146295b8624510d172deb0efa20edd..5e242f3abfa1df66c9fd69574208f87ce5bdf09c 100644
--- a/sandbox/win/src/process_mitigations.cc
+++ b/sandbox/win/src/process_mitigations.cc
@@ -308,7 +308,6 @@ bool CanSetProcessMitigationsPostStartup(MitigationFlags flags) {
                      MITIGATION_RELOCATE_IMAGE_REQUIRED |
                      MITIGATION_BOTTOM_UP_ASLR |
                      MITIGATION_STRICT_HANDLE_CHECKS |
-                     MITIGATION_WIN32K_DISABLE |
                      MITIGATION_EXTENSION_DLL_DISABLE |
                      MITIGATION_DLL_SEARCH_ORDER));
 }
@@ -316,7 +315,6 @@ bool CanSetProcessMitigationsPostStartup(MitigationFlags flags) {
 bool CanSetProcessMitigationsPreStartup(MitigationFlags flags) {
   // These mitigations cannot be enabled prior to startup.
   return !(flags & (MITIGATION_STRICT_HANDLE_CHECKS |
-                    MITIGATION_WIN32K_DISABLE |
                     MITIGATION_DLL_SEARCH_ORDER));
 }