Bug 1540288 - YouTube Tab Crash on macOS 10.11 in mozilla::PRemoteDecoderManagerChild::SendPRemoteDecoderConstructor r=Alex_Gaynor

Disable early sandbox init for the RDD Mac process until the 10.11 crash is resolved.

Differential Revision: https://phabricator.services.mozilla.com/D25690

--HG--
extra : moz-landing-system : lando

browser/app/profile/firefox.js

@@ -1048,7 +1048,7 @@ pref("security.sandbox.gmp.win32k-disable", false);
 // of when messaged by the parent after the message loop is running.
 pref("security.sandbox.content.mac.earlyinit", true);
 // Remove this pref once RDD early init is stable on Release.
-pref("security.sandbox.rdd.mac.earlyinit", true);
+pref("security.sandbox.rdd.mac.earlyinit", false);
 
 // This pref is discussed in bug 1083344, the naming is inspired from its
 // Windows counterpart, but on Mac it's an integer which means: