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

extensions/common/guest_view/guest_view_messages.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // IPC messages for GuestViews.
 // Multiply-included message file, hence no include guard.
 
 #include <string>
 
 #include "base/values.h"
@@ skipping 41 matching lines @@
                      int /* render_frame_id */,
                      std::string /* view_id */,
                      int /* element_instance_id */,
                      gfx::Size /* element_size */)
 
 // A renderer sends this message when it wants to resize a guest.
 IPC_MESSAGE_CONTROL3(GuestViewHostMsg_ResizeGuest,
                      int /* routing_id */,
                      int /* element_instance_id*/,
                      gfx::Size /* new_size */)
+
+// Tells a <webview> that its contentWindow is ready to be exposed.
+// The contentWindow should point to the RenderFrameProxy with routing
+// ID of |guest_proxy_routing_id|.
+IPC_MESSAGE_CONTROL2(GuestViewMsg_ContentWindowReady,
+                     int /* element_instance_id */,
+                     int /* guest_proxy_routing_id */)
+
+// We have a RenderFrame with routing id of |embedder_local_frame_routing_id|.
+// We want this local frame to be replaced with a remote frame that points
+// to a <webview>. This message will attach the local frame to the <webview>
+// guest. The <webview> is identified by its ID: |guest_instance_id|.
+IPC_MESSAGE_CONTROL3(GuestViewHostMsg_AttachLocalFrameToGuest,
+                     int /* embedder_local_frame_routing_id */,
+                     int /* element_instance_id */,
+                     int /* guest_instance_id */)