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

content/renderer/render_frame_proxy.cc

Index: content/renderer/render_frame_proxy.cc
diff --git a/content/renderer/render_frame_proxy.cc b/content/renderer/render_frame_proxy.cc
index ae6d699ae739783c76a70f4dcb05fcd246c45949..59317d808e7e85b404c91416dcd9cfe42cfc9eb4 100644
--- a/content/renderer/render_frame_proxy.cc
+++ b/content/renderer/render_frame_proxy.cc
@@ -140,6 +140,11 @@ RenderFrameProxy::~RenderFrameProxy() {
   g_routing_id_proxy_map.Get().erase(routing_id_);
 }
 
+void RenderFrameProxy::SetWebRemoteFrame(
+    blink::WebRemoteFrame* remote_frame) {
+  web_frame_ = remote_frame;
+}
+
 void RenderFrameProxy::Init(blink::WebRemoteFrame* web_frame,
                             RenderViewImpl* render_view) {
   CHECK(web_frame);