Bug 1403707 - Change content sandbox job level to JOB_LOCKDOWN. r=bobowen

Changing definition of Windows content sandbox level 4 (the current Nightly default) to increase the job level from JOB_RESTRICTED to JOB_LOCKDOWN.

security/sandbox/win/src/sandboxbroker/sandboxBroker.cpp

@@ -363,8 +363,8 @@ SandboxBroker::SetSecurityLevelForContentProcess(int32_t aSandboxLevel,
     accessTokenLevel = sandbox::USER_LOCKDOWN;
     initialIntegrityLevel = sandbox::INTEGRITY_LEVEL_LOW;
     delayedIntegrityLevel = sandbox::INTEGRITY_LEVEL_UNTRUSTED;
-  } else if (aSandboxLevel >= 10) {
-    jobLevel = sandbox::JOB_RESTRICTED;
+  } else if (aSandboxLevel >= 4) {
+    jobLevel = sandbox::JOB_LOCKDOWN;
     accessTokenLevel = sandbox::USER_LIMITED;
     initialIntegrityLevel = sandbox::INTEGRITY_LEVEL_LOW;
     delayedIntegrityLevel = sandbox::INTEGRITY_LEVEL_LOW;