Don't close background pages if there is a pending response (callback).

chrome/renderer/extensions/extension_process_bindings.h

Index: chrome/renderer/extensions/extension_process_bindings.h
diff --git a/chrome/renderer/extensions/extension_process_bindings.h b/chrome/renderer/extensions/extension_process_bindings.h
index df9165f00970561d64b80601954e9bd0ea6f4b1e..b37176deb1ee0ce5b91c02cbf82d3c855837d741 100644
--- a/chrome/renderer/extensions/extension_process_bindings.h
+++ b/chrome/renderer/extensions/extension_process_bindings.h
@@ -27,12 +27,15 @@ class ExtensionProcessBindings {
  public:
   static v8::Extension* Get(ExtensionDispatcher* extension_dispatcher);
 
-  // Handles a response to an API request.
+  // Handles a response to an API request.  Sets |extension_id|.
   static void HandleResponse(const ChromeV8ContextSet& contexts,
                              int request_id,
                              bool success,
                              const std::string& response,
-                             const std::string& error);
+                             const std::string& error,
+                             std::string* extension_id);
+
+  static bool HasPendingRequests(const std::string& extension_id);
 };
 
 #endif  // CHROME_RENDERER_EXTENSIONS_EXTENSION_PROCESS_BINDINGS_H_