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

chrome/browser/browser_main.cc

Index: chrome/browser/browser_main.cc
diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index ae82d1671a4173ca3eaaa786500f4e0242557f5a..943554fd5f36b0b45d406b84b809648fef294870 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -1902,15 +1902,6 @@ int BrowserMain(const MainFunctionParams& parameters) {
 #endif
 #endif
 
-  // Initialize extension event routers. Note that on Chrome OS, this will
-  // not succeed if the user has not logged in yet, in which case the
-  // event routers are initialized in LoginUtilsImpl::CompleteLogin instead.
-  if (profile->GetExtensionService()) {
-    // This will initialize bookmarks. Call it after bookmark import is done.
-    // See issue 40144.
-    profile->GetExtensionService()->InitEventRouters();
-  }
-
   // The extension service may be available at this point. If the command line
   // specifies --uninstall-extension, attempt the uninstall extension startup
   // action.