Prevent loading of session extensions into the sign-in profile

chrome/browser/extensions/extension_system_impl.cc

Index: chrome/browser/extensions/extension_system_impl.cc
diff --git a/chrome/browser/extensions/extension_system_impl.cc b/chrome/browser/extensions/extension_system_impl.cc
index ddaf85214ebd97e6b17fb672e8e6977095387042..ff266fc77a02b1e3cbd52d42bc25eb5a3bbfb08e 100644
--- a/chrome/browser/extensions/extension_system_impl.cc
+++ b/chrome/browser/extensions/extension_system_impl.cc
@@ -244,8 +244,10 @@ void ExtensionSystemImpl::Shared::Init(bool extensions_enabled) {
 
   bool skip_session_extensions = false;
 #if defined(OS_CHROMEOS)
-  // Skip loading session extensions if we are not in a user session.
-  skip_session_extensions = !chromeos::LoginState::Get()->IsUserLoggedIn();
+  // Skip loading session extensions if we are not in a user session or if the
+  // profile is the sign-in profile, which doesn't correspond to a user session.
+  skip_session_extensions = !chromeos::LoginState::Get()->IsUserLoggedIn() ||
+                            chromeos::ProfileHelper::IsSigninProfile(profile_);

[Devlin, 2017/04/10 15:40:54]

It's surprising to me that the user can be logged in while the active profile is
the signin profile... is that intentional?

[emaxx, 2017/04/11 12:12:36]

I think the sign-in profile (and the initial profile, which is the original
profile for the incognito sign-in profile) is always there. Maybe it's because
it hosts the stuff for the lock screen and the multiple sign-in.

   if (chrome::IsRunningInForcedAppMode()) {
     extension_service_->component_loader()->
         AddDefaultComponentExtensionsForKioskMode(skip_session_extensions);