Make extensions developer mode adhere to policy

chrome/browser/extensions/api/developer_private/developer_private_api.cc

Index: chrome/browser/extensions/api/developer_private/developer_private_api.cc
diff --git a/chrome/browser/extensions/api/developer_private/developer_private_api.cc b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
index 02cf2f17dff8d66e7f20873346a50f0a69ebda8d..b84fb85927e30047c87a70df66efb63a1baf814e 100644
--- a/chrome/browser/extensions/api/developer_private/developer_private_api.cc
+++ b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
@@ -164,9 +164,12 @@ std::unique_ptr<developer::ProfileInfo> CreateProfileInfo(Profile* profile) {
   std::unique_ptr<developer::ProfileInfo> info(new developer::ProfileInfo());
   info->is_supervised = profile->IsSupervised();
   PrefService* prefs = profile->GetPrefs();
+  const PrefService::Preference* pref =
+      prefs->FindPreference(prefs::kExtensionsUIDeveloperMode);
   info->is_incognito_available =
       IncognitoModePrefs::GetAvailability(prefs) !=
           IncognitoModePrefs::DISABLED;
+  info->is_developer_mode_disabled_by_policy = pref && pref->IsManaged();

[Bernhard Bauer, 2016/11/28 17:11:03]

When would the preference not be found? Usually we treat the set of registered
preferences as fixed at compile time, so a missing preference shouldn't (need
to) be handled. If there is a test that crashes here, you might have to register
preferences on the profile first?

[pmarko, 2016/11/29 12:40:21]

Good point, tests were working fine, this was just me being overly cautious
because I'm new :)
Done.

   info->in_developer_mode =
       !info->is_supervised &&
       prefs->GetBoolean(prefs::kExtensionsUIDeveloperMode);