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 10b26c595f7f4aebfae5ee5c4f6e88605ab35dd3..b65dc2a0834be6e5cc96046c9a6b6decb1b8d3bd 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -268,6 +268,16 @@ void Dispatcher::DidCreateScriptContext(
   const Extension* effective_extension =
       GetExtensionFromFrameAndWorld(frame, world_id, true);
 
+  bool extension_is_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 (extension_is_platform_app)
+    DCHECK(IsExtensionActive(extension_id));
+
   GURL frame_url = ScriptContext::GetDataSourceURLForFrame(frame);
   Feature::Context context_type =
       ClassifyJavaScriptContext(extension,
@@ -317,13 +327,12 @@ void Dispatcher::DidCreateScriptContext(
 
   UpdateBindingsForContext(context);
 
-  bool is_within_platform_app = IsWithinPlatformApp();
   // Inject custom JS into the platform app context.
-  if (is_within_platform_app) {
+  if (extension_is_platform_app) {
     module_system->Require("platformApp");
   }
 
-  delegate_->RequireAdditionalModules(context, is_within_platform_app);
+  delegate_->RequireAdditionalModules(context, extension_is_platform_app);
 
   VLOG(1) << "Num tracked contexts: " << script_context_set_.size();
 }