Create a RenderProcess message class and move keygen to it.

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 "base/memory/shared_memory.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_sequence.h"
@@ skipping 1146 matching lines @@
                     FrameMsg_PostMessage_Params)
 
 // Sent when the renderer displays insecure content in a secure origin.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidDisplayInsecureContent)
 
 // Sent when the renderer runs insecure content in a secure origin.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_DidRunInsecureContent,
                     std::string /* security_origin */,
                     GURL /* target URL */)
 
-// Asks the browser process to generate a keypair for grabbing a client
-// certificate from a CA (<keygen> tag), and returns the signed public
-// key and challenge string.
-IPC_SYNC_MESSAGE_CONTROL3_1(FrameHostMsg_Keygen,
-                            uint32 /* key size index */,
-                            std::string /* challenge string */,
-                            GURL /* URL of requestor */,
-                            std::string /* signed public key and challenge */)
-
 #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
 
 #if defined(OS_MACOSX)
 // Request that the browser load a font into shared memory for us.
 IPC_SYNC_MESSAGE_CONTROL1_3(FrameHostMsg_LoadFont,
                             FontDescriptor /* font to load */,
                             uint32 /* buffer size */,
                             base::SharedMemoryHandle /* font data */,
                             uint32 /* font id */)
 #elif defined(OS_WIN)
 // Request that the given font characters be loaded by the browser so it's
 // cached by the OS. Please see RenderMessageFilter::OnPreCacheFontCharacters
 // for details.
 IPC_SYNC_MESSAGE_CONTROL2_0(FrameHostMsg_PreCacheFontCharacters,
                             LOGFONT /* font_data */,
                             base::string16 /* characters */)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.