This defers starting background extension page RenderViews

chrome/browser/ui/startup/startup_browser_creator_impl.cc

Index: chrome/browser/ui/startup/startup_browser_creator_impl.cc
diff --git a/chrome/browser/ui/startup/startup_browser_creator_impl.cc b/chrome/browser/ui/startup/startup_browser_creator_impl.cc
index 3a7b5c32a9b8dcf15459b57acab0c990bc7198e0..59287b027d810c878632070ce1d781d228887fa9 100644
--- a/chrome/browser/ui/startup/startup_browser_creator_impl.cc
+++ b/chrome/browser/ui/startup/startup_browser_creator_impl.cc
@@ -32,6 +32,7 @@
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/extensions/extension_creator.h"
 #include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/extensions/pack_extension_job.h"
 #include "chrome/browser/first_run/first_run.h"
 #include "chrome/browser/google/google_util.h"
@@ -389,6 +390,14 @@ bool StartupBrowserCreatorImpl::Launch(Profile* profile,
     ShellIntegration::MigrateChromiumShortcuts();
 #endif  // defined(OS_WIN)
 
+#if defined(ENABLE_EXTENSIONS)
+  // If we deferred creation of background extension hosts, we want to create
+  // them now that the session (if any) has been restored.
+  ExtensionProcessManager* process_manager =
+      extensions::ExtensionSystem::Get(profile)->process_manager();
+  process_manager->DeferBackgroundHostCreation(false);
+#endif
+
   return true;
 }