Add an unimplemented history API to WebView

Source/web/WebFrameImpl.cpp

Index: Source/web/WebFrameImpl.cpp
diff --git a/Source/web/WebFrameImpl.cpp b/Source/web/WebFrameImpl.cpp
index b77f1206377c41769aa70062332ad392838b994e..07858eaa30a8f11248eb4af7171009397135d85a 100644
--- a/Source/web/WebFrameImpl.cpp
+++ b/Source/web/WebFrameImpl.cpp
@@ -2214,12 +2214,15 @@ PassRefPtr<LocalFrame> WebFrameImpl::createChildFrame(const FrameLoadRequest& re
 
     // If we're moving in the back/forward list, we might want to replace the content
     // of this child frame with whatever was there at that point.
-    HistoryItem* childItem = 0;
-    if (isBackForwardLoadType(frame()->loader().loadType()) && !frame()->document()->loadEventFinished())
-        childItem = frame()->page()->historyController().itemForNewChildFrame(childFrame.get());
+    RefPtr<HistoryItem> childItem;
+    if (isBackForwardLoadType(frame()->loader().loadType()) && !frame()->document()->loadEventFinished()) {
+        childItem = PassRefPtr<HistoryItem>(webframe->client()->historyItemForNewChildFrame(webframe));
+        if (!childItem)
+            childItem = frame()->page()->historyController().itemForNewChildFrame(childFrame.get());
+    }
 
     if (childItem)
-        childFrame->loader().loadHistoryItem(childItem);
+        childFrame->loader().loadHistoryItem(childItem.get());
     else
         childFrame->loader().load(FrameLoadRequest(0, request.resourceRequest(), "_self"));