Force-load a lazy background page whenever an extension is enabled.

chrome/browser/extensions/event_router.cc

Index: chrome/browser/extensions/event_router.cc
diff --git a/chrome/browser/extensions/event_router.cc b/chrome/browser/extensions/event_router.cc
index 213299b2f6c879663028f330231dd5427f0243b5..69be1f9c11fcb926ec66f77dab0883c790197fb9 100644
--- a/chrome/browser/extensions/event_router.cc
+++ b/chrome/browser/extensions/event_router.cc
@@ -65,6 +65,8 @@ void DispatchOnInstalledEvent(
                                                old_version, chrome_updated);
 }
 
+static void DoNothing(extensions::ExtensionHost* host) {}
+
 }  // namespace
 
 struct EventRouter::ListenerProcess {
@@ -128,6 +130,8 @@ EventRouter::EventRouter(Profile* profile, ExtensionPrefs* extension_prefs)
                  content::NotificationService::AllSources());
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSIONS_READY,
                  content::Source<Profile>(profile_));
+  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_ENABLED,
+                 content::Source<Profile>(profile_));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LOADED,
                  content::Source<Profile>(profile_));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
@@ -606,6 +610,18 @@ void EventRouter::Observe(int type,
       dispatch_chrome_updated_event_ = false;
       break;
     }
+    case chrome::NOTIFICATION_EXTENSION_ENABLED: {
+      // If the extension has a lazy background page, make sure it gets loaded
+      // to register the events the extension is interested in.
+      const Extension* extension =
+          content::Details<const Extension>(details).ptr();
+      if (extension->has_lazy_background_page()) {
+        LazyBackgroundTaskQueue* queue =
+            ExtensionSystem::Get(profile_)->lazy_background_task_queue();
+        queue->AddPendingTask(profile_, extension->id(),
+                              base::Bind(&DoNothing));

[Matt Perry, 2012/11/29 22:03:21]

Do you actually need to have an empty function? What if you pass
base::Callback()?

[Marijn Kruisselbrink, 2012/11/30 00:51:20]

base::Callback() is "null", which means that unless the code invoking it first
checks for is_null, calling Run on it will crash. So yes, unfortunately the
empty function is really needed. (I first tried to just load the background
page, without posting a task at all, but LazyBackgroundTaskQueue crashes if the
background page got loaded with no tasks pending).

+      }
+    }
     case chrome::NOTIFICATION_EXTENSION_LOADED: {
       // Add all registered lazy listeners to our cache.
       const Extension* extension =