Enable login screen apps.

extensions/browser/process_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/process_manager.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 347 matching lines @@
 bool ProcessManager::CreateBackgroundHost(const Extension* extension,
                                           const GURL& url) {
   // Hosted apps are taken care of from BackgroundContentsService. Ignore them
   // here.
   if (extension->is_hosted_app())
     return false;
 
   // Don't create hosts if the embedder doesn't allow it.
   ProcessManagerDelegate* delegate =
       ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
-  if (delegate && !delegate->IsBackgroundPageAllowed(browser_context_))
+  if (delegate &&
+      !delegate->IsBackgroundPageAllowed(browser_context_, extension))

[Devlin, 2017/03/13 19:39:35]

We check this in three different places now, making it a bit redundant. :)

[achuithb, 2017/03/15 00:40:25]

It does seem that way :/

What would you propose?

     return false;
 
   // Don't create multiple background hosts for an extension.
   if (GetBackgroundHostForExtension(extension->id()))
     return true;  // TODO(kalman): return false here? It might break things...
 
   ExtensionHost* host =
       new ExtensionHost(extension, GetSiteInstanceForURL(url).get(), url,
                         VIEW_TYPE_EXTENSION_BACKGROUND_PAGE);
   host->CreateRenderViewSoon();
   OnBackgroundHostCreated(host);
   return true;
 }
 
 void ProcessManager::MaybeCreateStartupBackgroundHosts() {
   if (startup_background_hosts_created_)
     return;
 
   // The embedder might disallow background pages entirely.
   ProcessManagerDelegate* delegate =
       ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
-  if (delegate && !delegate->IsBackgroundPageAllowed(browser_context_))
+  if (delegate && !delegate->IsBackgroundPageAllowed(browser_context_, nullptr))

[achuithb, 2017/03/15 00:40:25]

We could potentially drop this check since we check again in
CreateStartupBackgroundHosts.

I'm just worried about changing a lot of behavior here since this code is quite
tricky, and does different things in different contexts on different platforms. 

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

This one is somewhat beneficial, since it helps us early-out if no background
pages are allowed.  But we should change it to
AreBackgroundPagesAllowedForContext() (see also comment in the delegate file).

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

Done.

     return;
 
   // The embedder might want to defer background page loading. For example,
   // Chrome defers background page loading when it is launched to show the app
   // list, then triggers a load later when a browser window opens.
   if (delegate &&
       delegate->DeferCreatingStartupBackgroundHosts(browser_context_))
     return;
 
   CreateStartupBackgroundHosts();
@@ skipping 295 matching lines @@
     const Extension* extension,
     UnloadedExtensionInfo::Reason reason) {
   ExtensionHost* host = GetBackgroundHostForExtension(extension->id());
   if (host != nullptr)
     CloseBackgroundHost(host);
   UnregisterExtension(extension->id());
 }
 
 void ProcessManager::CreateStartupBackgroundHosts() {
   DCHECK(!startup_background_hosts_created_);
+  ProcessManagerDelegate* delegate =
+      ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
   for (const scoped_refptr<const Extension>& extension :
            extension_registry_->enabled_extensions()) {
-    CreateBackgroundHostForExtensionLoad(this, extension.get());
+    if (delegate &&
+        delegate->IsBackgroundPageAllowed(browser_context_, extension.get()))

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

This one should be able to be avoided - we'll check whether or not its allowed
when we try to create it in CreateBackgroundHost().

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

Done.

+      CreateBackgroundHostForExtensionLoad(this, extension.get());
     for (auto& observer : observer_list_)
       observer.OnBackgroundHostStartup(extension.get());
   }
 }
 
 void ProcessManager::OnBackgroundHostCreated(ExtensionHost* host) {
   DCHECK_EQ(browser_context_, host->browser_context());
   background_hosts_.insert(host);
 
   if (BackgroundInfo::HasLazyBackgroundPage(host->extension())) {
@@ skipping 271 matching lines @@
   if (extension && !IncognitoInfo::IsSplitMode(extension)) {
     BrowserContext* original_context =
         ExtensionsBrowserClient::Get()->GetOriginalContext(browser_context());
     return ProcessManager::Get(original_context)->GetSiteInstanceForURL(url);
   }
 
   return ProcessManager::GetSiteInstanceForURL(url);
 }
 
 }  // namespace extensions