Unrevert again r119770 - "Event pages: remember events that the page registered for,""

chrome/browser/extensions/extension_event_router.h

Index: chrome/browser/extensions/extension_event_router.h
diff --git a/chrome/browser/extensions/extension_event_router.h b/chrome/browser/extensions/extension_event_router.h
index 6624d98efdf0a1dc2a83a6b6d04c3eefc7f00ea3..b142198338a761bed5ea9089ed0a3e61dfad1b4a 100644
--- a/chrome/browser/extensions/extension_event_router.h
+++ b/chrome/browser/extensions/extension_event_router.h
@@ -50,6 +50,15 @@ class ExtensionEventRouter : public content::NotificationObserver {
                            content::RenderProcessHost* process,
                            const std::string& extension_id);
 
+  // Add or remove the extension as having a lazy background page that listens
+  // to the event. The difference from the above methods is that these will be
+  // remembered even after the process goes away. We use this list to decide
+  // which extension pages to load when dispatching an event.
+  void AddLazyEventListener(const std::string& event_name,
+                            const std::string& extension_id);
+  void RemoveLazyEventListener(const std::string& event_name,
+                               const std::string& extension_id);
+
   // Returns true if there is at least one listener for the given event.
   bool HasEventListener(const std::string& event_name);
 
@@ -105,15 +114,25 @@ class ExtensionEventRouter : public content::NotificationObserver {
   // Shared by DispatchEvent*. If |extension_id| is empty, the event is
   // broadcast.
   // An event that just came off the pending list may not be delayed again.
-  void DispatchEventImpl(const linked_ptr<ExtensionEvent>& event,
+  void DispatchEventImpl(const std::string& extension_id,
+                         const linked_ptr<ExtensionEvent>& event,
                          bool was_pending);
 
+  // Ensures that all non-persistent background pages that are interested in the
+  // given event are loaded, and queues the event if the page is not ready yet.
+  // If |extension_id| is non-empty, we load only that extension's page
+  // (assuming it is interested in the event).
+  void LoadLazyBackgroundPagesForEvent(
+      const std::string& extension_id,
+      const linked_ptr<ExtensionEvent>& event);
+
   // Dispatch may be delayed if the extension has a lazy background page.
-  bool CanDispatchEventNow(const std::string& extension_id);
+  bool CanDispatchEventNow(const Extension* extension);
 
   // Store the event so that it can be dispatched (in order received)
   // when the background page is done loading.
-  void AppendEvent(const linked_ptr<ExtensionEvent>& event);
+  void AppendEvent(const std::string& extension_id,
+                   const linked_ptr<ExtensionEvent>& event);
   void DispatchPendingEvents(const std::string& extension_id);
 
  private:
@@ -135,6 +154,11 @@ class ExtensionEventRouter : public content::NotificationObserver {
   typedef std::map<std::string, std::set<EventListener> > ListenerMap;
   ListenerMap listeners_;
 
+  // Keeps track of all the non-persistent background pages that are listening
+  // to events.
+  // TODO(mpcomplete): save to disk.
+  ListenerMap lazy_listeners_;
+
   // A map between an extension id and the queue of events pending
   // the load of it's background page.
   typedef std::vector<linked_ptr<ExtensionEvent> > PendingEventsList;