Start the extension event routers for each profile, not just at browser startup.

chrome/browser/extensions/extension_browser_event_router.cc

Index: chrome/browser/extensions/extension_browser_event_router.cc
diff --git a/chrome/browser/extensions/extension_browser_event_router.cc b/chrome/browser/extensions/extension_browser_event_router.cc
index 66a2cf01501549ad6be4a7c921d3533c1dbc688d..9b723d30822efb7a9b8a989d2733e30296536633 100644
--- a/chrome/browser/extensions/extension_browser_event_router.cc
+++ b/chrome/browser/extensions/extension_browser_event_router.cc
@@ -115,13 +115,13 @@ ExtensionBrowserEventRouter::~ExtensionBrowserEventRouter() {
 }
 
 void ExtensionBrowserEventRouter::OnBrowserAdded(const Browser* browser) {
-  if (!profile_->IsSameProfile(browser->profile()))
-    return;
   RegisterForBrowserNotifications(browser);
 }
 
 void ExtensionBrowserEventRouter::RegisterForBrowserNotifications(
     const Browser* browser) {
+  if (!profile_->IsSameProfile(browser->profile()))
+    return;
   // Start listening to TabStripModel events for this browser.
   browser->tabstrip_model()->AddObserver(this);