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

content/browser/frame_host/render_frame_proxy_host.cc

Index: content/browser/frame_host/render_frame_proxy_host.cc
diff --git a/content/browser/frame_host/render_frame_proxy_host.cc b/content/browser/frame_host/render_frame_proxy_host.cc
index f0f5808f74fecacce8b0224e4fb4b311ec91de8d..b78fb2002143db5a7c72ff5b19dbe6139af96544 100644
--- a/content/browser/frame_host/render_frame_proxy_host.cc
+++ b/content/browser/frame_host/render_frame_proxy_host.cc
@@ -60,11 +60,17 @@ RenderFrameProxyHost::RenderFrameProxyHost(SiteInstance* site_instance,
   CHECK(render_view_host_);
   frame_tree_node_->frame_tree()->AddRenderViewHostRef(render_view_host_);
 
-  if (!frame_tree_node_->IsMainFrame() &&
-      frame_tree_node_->parent()
-              ->render_manager()
-              ->current_frame_host()
-              ->GetSiteInstance() == site_instance) {
+  bool is_proxy_to_parent = !frame_tree_node_->IsMainFrame() &&
+                            frame_tree_node_->parent()
+                                    ->render_manager()
+                                    ->current_frame_host()
+                                    ->GetSiteInstance() == site_instance;
+
+  // If this is a proxy to parent frame or this proxy is for the inner
+  // WebContents's FrameTreeNode in outer WebContents's process, then we need a
+  // CrossProcessFrameConnector.
+  if (is_proxy_to_parent ||
+      frame_tree_node_->render_manager()->ForInnerDelegate()) {
     // The RenderFrameHost navigating cross-process is destroyed and a proxy for
     // it is created in the parent's process. CrossProcessFrameConnector
     // initialization only needs to happen on an initial cross-process