Make <webview> use out-of-process iframe architecture.

content/browser/frame_host/render_frame_proxy_host.h

Index: content/browser/frame_host/render_frame_proxy_host.h
diff --git a/content/browser/frame_host/render_frame_proxy_host.h b/content/browser/frame_host/render_frame_proxy_host.h
index 964750691590097a83f9ac91972fc406ce43110a..534118dfa4bca50e5770091a8b3f772711bd0109 100644
--- a/content/browser/frame_host/render_frame_proxy_host.h
+++ b/content/browser/frame_host/render_frame_proxy_host.h
@@ -69,6 +69,9 @@ class RenderFrameProxyHost
   // for the SiteInstance.
   bool InitRenderFrameProxy();
 
+  void SetOverriddenParentFTNID(
+      int64 pseudo_parent_frame_tree_node_id);
+
   int GetRoutingID() {
     return routing_id_;
   }
@@ -135,6 +138,8 @@ class RenderFrameProxyHost
   // True if we have a live RenderFrameProxy for this host.
   bool render_frame_proxy_created_;
 
+  int64 pseudo_parent_frame_tree_node_id_;
+
   // When a RenderFrameHost is in a different process from its parent in the
   // frame tree, this class connects its associated RenderWidgetHostView
   // to this RenderFrameProxyHost, which corresponds to the same frame in the