Make it possible for the embedder to run unload handlers in subframes.

Source/core/loader/FrameLoader.h

Index: Source/core/loader/FrameLoader.h
diff --git a/Source/core/loader/FrameLoader.h b/Source/core/loader/FrameLoader.h
index 6b37b6fa6c0b29fe206715e85b8f22064c06693a..728996b9db0657f78847acea075b68a51745e26a 100644
--- a/Source/core/loader/FrameLoader.h
+++ b/Source/core/loader/FrameLoader.h
@@ -46,6 +46,10 @@
 #include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 
+namespace blink {
+class WebViewImpl;
+}
+
 namespace WebCore {
 
 class Resource;
@@ -204,6 +208,8 @@ public:
     void restoreScrollPositionAndViewState(RestorePolicy = StandardRestore);
 
 private:
+    friend class blink::WebViewImpl;
+
     bool allChildrenAreComplete() const; // immediate children, not all descendants
 
     void completed();