Remove unused did_defer_for_testing() from CrossSiteResourceHandler.

content/browser/loader/cross_site_resource_handler.h

Index: content/browser/loader/cross_site_resource_handler.h
diff --git a/content/browser/loader/cross_site_resource_handler.h b/content/browser/loader/cross_site_resource_handler.h
index 2f7022527f1b7d768f3ada1a54380e15e34bab23..b73a5a1475b799e0493ea87bd0311e2ff7638f55 100644
--- a/content/browser/loader/cross_site_resource_handler.h
+++ b/content/browser/loader/cross_site_resource_handler.h
@@ -49,9 +49,6 @@ class CrossSiteResourceHandler : public LayeredResourceHandler {
   CONTENT_EXPORT static void SetLeakRequestsForTesting(
       bool leak_requests_for_testing);
 
-  // Returns whether the handler is deferred.
-  bool did_defer_for_testing() const { return did_defer_; }
-
  private:
   // Prepare to transfer the cross-site response to a new RenderFrameHost, by
   // asking it to issue an identical request (on the UI thread).