Extensions: DCHECK that all app pages are blessed before use.

extensions/renderer/dispatcher.cc

Index: extensions/renderer/dispatcher.cc
diff --git a/extensions/renderer/dispatcher.cc b/extensions/renderer/dispatcher.cc
index 44b2fd0f96e818a1bf056574ab16224c2ad99ab8..6e087ac39f6effd9aca1ea099043f7e90ea26562 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -257,6 +257,16 @@ void Dispatcher::DidCreateScriptContext(
     extension_id = "";
   }
 
+  bool is_within_platform_app = extension && extension->is_platform_app();
+
+  // If we are navigating to a platform app URL, the extension must first have
+  // been activated. If not, IsWithinPlatformApp will incorrectly return false,
+  // and we will be missing information about what features the app has.
+  // (Note: This DCHECK is invalid for non-app extensions, which do not get
+  // activated in "unblessed" contexts such as content scripts and iframes.)
+  if (is_within_platform_app)
+    DCHECK(IsExtensionActive(extension_id));

[not at google - send to devlin, 2014/07/07 14:45:55]

Good idea. A slightly stronger check would be to move the DCHECK to line 275 and
make it DCHECK_EQ(Feature::BLESSED_EXTENSION_CONTEXT, context_type) because an
extension being active doesn't necessarily imply that it's a blessed context (as
Sam already pointed out, iframes) - yet specifically all app contexts must be
privileged, at least in the current design where apps can't be hosted in
untrusted processes.

I think the comment could be just "Sanity check that all platform app contexts
are blessed".

as a nit I'd request you call the variable "is_platform_app_context" to avoid
mixing it up with IsWithinPlatformApp.

[Matt Giuca, 2014/07/10 08:04:56]

Done.

+
   Feature::Context context_type =
       ClassifyJavaScriptContext(extension,
                                 extension_group,
@@ -296,7 +306,6 @@ void Dispatcher::DidCreateScriptContext(
 
   UpdateBindingsForContext(context);
 
-  bool is_within_platform_app = IsWithinPlatformApp();
   // Inject custom JS into the platform app context.
   if (is_within_platform_app) {
     module_system->Require("platformApp");