Require WebLocalFrame to be created with a non-null client

extensions/renderer/scoped_web_frame.h

Index: extensions/renderer/scoped_web_frame.h
diff --git a/extensions/renderer/scoped_web_frame.h b/extensions/renderer/scoped_web_frame.h
index 948a289483bf174fdb6369ccd194577865835f4e..ebcc877994f7a471df363bbcfd47349c8586f5e2 100644
--- a/extensions/renderer/scoped_web_frame.h
+++ b/extensions/renderer/scoped_web_frame.h
@@ -6,6 +6,7 @@
 #define SCOPED_WEB_FRAME_H_
 
 #include "base/macros.h"
+#include "third_party/WebKit/public/web/WebFrameClient.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
 #include "third_party/WebKit/public/web/WebView.h"
 
@@ -21,12 +22,15 @@ public:
   blink::WebLocalFrame* frame() { return frame_; }
 
 private:
-  // The webview and the frame are kept alive by the ScopedWebFrame
-  // because they are not destructed unless ~ScopedWebFrame explicitly
-  // closes the webview and the frame.
-  blink::WebView* view_;
-  blink::WebLocalFrame* frame_;
-  DISALLOW_COPY_AND_ASSIGN(ScopedWebFrame);
+ blink::WebFrameClient frame_client_;
+
+ // The webview and the frame are kept alive by the ScopedWebFrame
+ // because they are not destructed unless ~ScopedWebFrame explicitly
+ // closes the WebView.
+ blink::WebView* view_;
+ blink::WebLocalFrame* frame_;
+
+ DISALLOW_COPY_AND_ASSIGN(ScopedWebFrame);
 };
 
 }  // namespace extensions