Clear opener when frame is detached.

third_party/WebKit/public/web/WebFrame.h

Index: third_party/WebKit/public/web/WebFrame.h
diff --git a/third_party/WebKit/public/web/WebFrame.h b/third_party/WebKit/public/web/WebFrame.h
index 619764328532452b78941053dd3c5b5c783e85fb..97c77283499f92ac21a878d39e5592f08dd84a47 100644
--- a/third_party/WebKit/public/web/WebFrame.h
+++ b/third_party/WebKit/public/web/WebFrame.h
@@ -112,7 +112,7 @@ class WebFrame {
   // This method closes and deletes the WebFrame. This is typically called by
   // the embedder in response to a frame detached callback to the WebFrame
   // client.
-  virtual void close() = 0;
+  virtual void close();
 
   // Called by the embedder when it needs to detach the subtree rooted at this
   // frame.
@@ -439,7 +439,6 @@ class WebFrame {
   bool inShadowTree() const { return m_scope == WebTreeScopeType::Shadow; }
 
   static void traceFrames(Visitor*, WebFrame*);
-  void clearWeakFrames(Visitor*);
 #endif
 
  protected:
@@ -458,7 +457,6 @@ class WebFrame {
   friend class WebFrameTest;
 
   static void traceFrame(Visitor*, WebFrame*);
-  static bool isFrameAlive(const WebFrame*);
 #endif
 
   const WebTreeScopeType m_scope;