Send a subtree of same-process PageStates for back/forward child frames.

content/renderer/render_frame_impl.h

Index: content/renderer/render_frame_impl.h
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index bcde1e4e44371f061aff51179d135a2844fbc94d..90ae8e910a7bdaffbbe03ac03af983baeafd93ed 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -1125,20 +1125,6 @@ class CONTENT_EXPORT RenderFrameImpl
   // didCreateDataSource().
   std::unique_ptr<NavigationParams> pending_navigation_params_;
 
-  // Keeps track of which future subframes the browser process has history items
-  // for during a history navigation, as well as whether those items are for
-  // about:blank.  The renderer process should ask the browser for history items
-  // when subframes with these names are created (as long as they are not
-  // staying at about:blank), and directly load the initial URLs for any other
-  // subframes.
-  //
-  // This state is incrementally cleared as it is used and then reset in
-  // didStopLoading, since it is not needed after the first load completes and
-  // is never used after the initial navigation.
-  // TODO(creis): Expand this to include any corresponding same-process
-  // PageStates for the whole subtree in https://crbug.com/639842.
-  std::map<std::string, bool> history_subframe_unique_names_;
-
   // Stores the current history item for this frame, so that updates to it can
   // be reported to the browser process via SendUpdateState.
   blink::WebHistoryItem current_history_item_;