Fix race condition where chrome.tabs.executeScript sometimes wouldn't

chrome/renderer/navigation_state.h

Index: chrome/renderer/navigation_state.h
diff --git a/chrome/renderer/navigation_state.h b/chrome/renderer/navigation_state.h
index ab34b123b08d2a8b967c82d4ae799b894fd0b62d..a25d4cbaf37e23427c3160d8c8babd343d3387e6 100644
--- a/chrome/renderer/navigation_state.h
+++ b/chrome/renderer/navigation_state.h
@@ -66,6 +66,7 @@ class NavigationState : public WebKit::WebDataSource::ExtraData {
     return user_script_idle_scheduler_.get();
   }
   void set_user_script_idle_scheduler(UserScriptIdleScheduler* scheduler);
+  void swap_user_script_idle_scheduler(NavigationState* state);
 
   // Contains the page_id for this navigation or -1 if there is none yet.
   int32 pending_page_id() const { return pending_page_id_; }