Enable Isolate Extensions by default.

chrome/common/extensions/extension_process_policy.cc

Index: chrome/common/extensions/extension_process_policy.cc
diff --git a/chrome/common/extensions/extension_process_policy.cc b/chrome/common/extensions/extension_process_policy.cc
index 59fb528efd9031584886a596fefe89828bc9aaf7..5b2c81402c7599413d1ee5b160610353e168ada2 100644
--- a/chrome/common/extensions/extension_process_policy.cc
+++ b/chrome/common/extensions/extension_process_policy.cc
@@ -79,8 +79,8 @@ bool IsIsolateExtensionsEnabled() {
   const std::string group_name =
       base::FieldTrialList::FindFullName("SiteIsolationExtensions");
   // Use StartsWith() for more flexibility (e.g. multiple Enabled groups).
-  return base::StartsWith(group_name, "Enabled",
-                          base::CompareCase::INSENSITIVE_ASCII);
+  return !base::StartsWith(group_name, "Control",
+                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 }  // namespace extensions