Oilpan: extend tracing over WebFrame trees.

public/web/WebFrame.h

Index: public/web/WebFrame.h
diff --git a/public/web/WebFrame.h b/public/web/WebFrame.h
index 285434df91db20877b5226d85b557c0f05a8b7b5..63215a4738730dd9d245d3131f0174c59af2e5ea 100644
--- a/public/web/WebFrame.h
+++ b/public/web/WebFrame.h
@@ -657,16 +657,26 @@ public:
 
 #if BLINK_IMPLEMENTATION
     static WebFrame* fromFrame(Frame*);
-    static void traceChildren(Visitor*, WebFrame*);
+#if ENABLE(OILPAN)
+    static void traceFrames(Visitor*, WebFrame*);
+    void clearWeakFrames(Visitor*);
+#endif
 #endif
 
 protected:
-    explicit WebFrame();
+    WebFrame();
     virtual ~WebFrame();
 
 private:
     friend class OpenedFrameTracker;
 
+#if BLINK_IMPLEMENTATION
+#if ENABLE(OILPAN)
+    static void traceFrame(Visitor*, WebFrame*);
+    static bool isAlive(Visitor*, WebFrame*);
+#endif
+#endif
+
     WebFrame* m_parent;
     WebFrame* m_previousSibling;
     WebFrame* m_nextSibling;