Fix webrequest api for webview in webui

extensions/browser/guest_view/guest_view_base.h

Index: extensions/browser/guest_view/guest_view_base.h
diff --git a/extensions/browser/guest_view/guest_view_base.h b/extensions/browser/guest_view/guest_view_base.h
index e8b0fa80401a9de4e257fba23d1881f1ba4dc400..48aa36e8f36d72855855c5ca91c26662183d01f9 100644
--- a/extensions/browser/guest_view/guest_view_base.h
+++ b/extensions/browser/guest_view/guest_view_base.h
@@ -87,6 +87,12 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
   // completed loading.
   virtual void DidStopLoading() {}
 
+  // This method is called before the guest will be detached from its embedder.
+  // |embedder_web_contents_| should still be valid during this call. This
+  // allows the derived class to perform some cleanup related to the embedder
+  // web contents.
+  virtual void WillDetachFromEmbedder() {}
+
   // This method is called when the guest's embedder WebContents has been
   // destroyed and the guest will be destroyed shortly.
   //