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

content/common/frame_messages.h

 // Copyright 2013 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 interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/common/frame_message_enums.h"
@@ skipping 557 matching lines @@
                     content::RequestNavigationParams /* request_params */)
 
 // PlzNavigate
 // Tells the renderer that a navigation failed with the error code |error_code|
 // and that the renderer should display an appropriate error page.
 IPC_MESSAGE_ROUTED4(FrameMsg_FailedNavigation,
                     content::CommonNavigationParams,  /* common_params */
                     content::RequestNavigationParams, /* request_params */
                     bool,                             /* stale_copy_in_cache */
                     int                               /* error_code */)
+// Replace this frame with a RenderFrameProxy whose routing ID is

[Charlie Reis, 2015/04/30 23:06:47]

nit: Blank line before.

[lazyboy, 2015/05/05 07:28:15]

Done.

+// |proxy_routing_id|.
+// The proxy is for a frame in guest that lives in embedder process.

[Charlie Reis, 2015/04/30 23:06:47]

nit: Move to previous line.
Also rephrase:
The proxy is a placeholder in the embedder's process for a guest's main frame.

[lazyboy, 2015/05/05 07:28:15]

Done.

+IPC_MESSAGE_ROUTED1(FrameMsg_ReplaceLocalFrameWithProxy,

[Charlie Reis, 2015/04/30 23:06:47]

This should probably be listed next to SwapOut.

[lazyboy, 2015/05/05 07:28:15]

Done.

+                    int32 /* proxy_routing_id */)
 
 #if defined(ENABLE_PLUGINS)
 // Notifies the renderer of updates to the Plugin Power Saver origin whitelist.
 IPC_MESSAGE_ROUTED1(FrameMsg_UpdatePluginContentOriginWhitelist,
                     std::set<GURL> /* origin_whitelist */)
 #endif  // defined(ENABLE_PLUGINS)
 
 // -----------------------------------------------------------------------------
 // Messages sent from the renderer to the browser.
 
@@ skipping 314 matching lines @@
                     FrameMsg_PostMessage_Params)
 
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
 
 // Message to show/hide a popup menu using native controls.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ShowPopup,
                     FrameHostMsg_ShowPopup_Params)
 IPC_MESSAGE_ROUTED0(FrameHostMsg_HidePopup)
 
 #endif