Prerendered pages are swapped in at browser::Navigate time.

chrome/common/render_messages.h

 // Copyright (c) 2012 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.
 
 // Multiply-included file, no traditional include guard.
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 289 matching lines @@
                     std::string, /* BCP 47/RFC 5646 language code the page
                                     is in */
                     std::string /* BCP 47/RFC 5646 language code to translate
                                    to */)
 
 // Tells the renderer to revert the text of translated page to its original
 // contents.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_RevertTranslation,
                     int /* page id */)
 
-// Tells a renderer if it's currently being prerendered.  Must only be set
-// to true before any navigation occurs, and only set to false at most once
-// after that.
-IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetIsPrerendering,
-                    bool /* whether the RenderView is prerendering */)
-
 // Sent on process startup to indicate whether this process is running in
 // incognito mode.
 IPC_MESSAGE_CONTROL1(ChromeViewMsg_SetIsIncognitoProcess,
                      bool /* is_incognito_processs */)
 
 // Sent in response to ViewHostMsg_DidBlockDisplayingInsecureContent.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetAllowDisplayingInsecureContent,
                     bool /* allowed */)
 
 // Sent in response to ViewHostMsg_DidBlockRunningInsecureContent.
@@ skipping 303 matching lines @@
 // previous SetCookie message to be processed.
 IPC_SYNC_MESSAGE_ROUTED2_1(ChromeViewHostMsg_GetCookies,
                            GURL /* url */,
                            GURL /* first_party_for_cookies */,
                            std::string /* cookies */)
 
 // Provide the browser process with current renderer framerate.
 IPC_MESSAGE_CONTROL2(ChromeViewHostMsg_FPS,
                      int /* routing id */,
                      float /* frames per second */)