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..333a34de76790ef25be44539939b1cc9690b7a68 100644
--- a/chrome/common/extensions/extension_process_policy.cc
+++ b/chrome/common/extensions/extension_process_policy.cc
@@ -79,8 +79,14 @@ 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);
+  bool control_group = base::StartsWith(group_name, "Control",
+                                        base::CompareCase::INSENSITIVE_ASCII);
+  bool default_group = base::StartsWith(group_name, "Default",
+                                        base::CompareCase::INSENSITIVE_ASCII);
+  if (control_group || default_group)

[Devlin, 2017/02/27 19:27:22]

It's strange to me that the default_group behavior doesn't match the "default"
behavior - is this intentional?  Do we have a default group with a population? 
If not, I think it'd make more sense to only gate on Control.

[nasko, 2017/02/27 19:35:14]

Yes, naming is hard ... the "default" group should've been called a "remainder"
group, which is the part of the population that wasn't either Control or
Enabled. Default group removed.

+    return false;
+
+  return true;
 }
 
 }  // namespace extensions