Enable login screen apps.

extensions/browser/process_manager_delegate.h

Index: extensions/browser/process_manager_delegate.h
diff --git a/extensions/browser/process_manager_delegate.h b/extensions/browser/process_manager_delegate.h
index 7cc48c0af74ee81ab9db0e1eddc88bcbe1580e10..7a8d50d8788fd68e333c4fdd85cfda7f4d276f55 100644
--- a/extensions/browser/process_manager_delegate.h
+++ b/extensions/browser/process_manager_delegate.h
@@ -11,15 +11,17 @@ class BrowserContext;
 
 namespace extensions {
 
+class Extension;
+
 // Customization of ProcessManager for the extension system embedder.
 class ProcessManagerDelegate {
  public:
   virtual ~ProcessManagerDelegate() {}
 
   // Returns true if the embedder allows background pages for the given
-  // |context|.
-  virtual bool IsBackgroundPageAllowed(
-      content::BrowserContext* context) const = 0;
+  // |context|, and a given |extension|, which can optionally be nullptr.
+  virtual bool IsBackgroundPageAllowed(content::BrowserContext* context,

[Devlin, 2017/03/17 16:37:23]

Let's break this into two functions:
bool AreBackgroundPagesAllowedForContext(content::BrowserContext* context)
and
bool IsExtensionBackgroundPageAllowed(content::BrowserContext* context, const
Extension& extension)

That way, it's clear what the semantics and meaning of each is, and it prevents
us from having to deal with null extensions.  (And for the non-chromeos version
of IsExtensionBackgroundPageAllowed(), it would just return
AreBackgroundPagesAllowedForContext())

[achuithb, 2017/03/22 00:15:53]

Done.

+                                       const Extension* extension) const = 0;
 
   // Returns true if the embedder wishes to defer starting up the renderers for
   // extension background pages. If the embedder returns true it must call