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

extensions/common/guest_view/extensions_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 extensions GuestViews.
 // Multiply-included message file, hence no include guard.
 
 #include <string>
 
 #include "ipc/ipc_message_macros.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/ipc/gfx_param_traits.h"
 
 #define IPC_MESSAGE_START ExtensionsGuestViewMsgStart
 // Messages sent from the browser to the renderer.
 
 // The ACK for GuestViewHostMsg_CreateMimeHandlerViewGuest.
 IPC_MESSAGE_CONTROL1(ExtensionsGuestViewMsg_CreateMimeHandlerViewGuestACK,
                      int /* element_instance_id */)
 
 // Once a MimeHandlerView guest's JavaScript onload function has been called,
 // this IPC is sent to the container to notify it.
 IPC_MESSAGE_CONTROL1(ExtensionsGuestViewMsg_MimeHandlerViewGuestOnLoadCompleted,
                      int /* element_instance_id */)
 
+// Tells a <webview> that its contentWindow is ready to be exposed.
+IPC_MESSAGE_CONTROL1(ExtensionsGuestViewMsg_ContentWindowReady,
+                     int /* element_instance_id */)
+
 // Messages sent from the renderer to the browser.
 
+// 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(ExtensionsGuestViewHostMsg_AttachToEmbedderFrame,
+                     int /* embedder_local_frame_routing_id */,
+                     int /* element_instance_id */,
+                     int /* guest_instance_id */)
+
 // Queries whether the RenderView of the provided |routing_id| is allowed to
 // inject the script with the provided |script_id|.
 IPC_SYNC_MESSAGE_CONTROL2_1(
     ExtensionsGuestViewHostMsg_CanExecuteContentScriptSync,
     int /* routing_id */,
     int /* script_id */,
     bool /* allowed */)
 
 // Tells the browser to create a mime handler guest view for a plugin.
 IPC_MESSAGE_CONTROL4(ExtensionsGuestViewHostMsg_CreateMimeHandlerViewGuest,
                      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(ExtensionsGuestViewHostMsg_ResizeGuest,
                      int /* routing_id */,
                      int /* element_instance_id*/,
                      gfx::Size /* new_size */)