Remove dead DocumentState metrics tracking code

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 351 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(redirect_start)
   IPC_STRUCT_TRAITS_MEMBER(redirect_end)
   IPC_STRUCT_TRAITS_MEMBER(fetch_start)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(content::RequestNavigationParams)
   IPC_STRUCT_TRAITS_MEMBER(is_overriding_user_agent)
   IPC_STRUCT_TRAITS_MEMBER(redirects)
   IPC_STRUCT_TRAITS_MEMBER(redirect_response)
   IPC_STRUCT_TRAITS_MEMBER(can_load_local_resources)
-  IPC_STRUCT_TRAITS_MEMBER(request_time)
   IPC_STRUCT_TRAITS_MEMBER(page_state)
   IPC_STRUCT_TRAITS_MEMBER(nav_entry_id)
   IPC_STRUCT_TRAITS_MEMBER(is_same_document_history_load)
   IPC_STRUCT_TRAITS_MEMBER(is_history_navigation_in_new_child)
   IPC_STRUCT_TRAITS_MEMBER(subframe_unique_names)
   IPC_STRUCT_TRAITS_MEMBER(has_committed_real_load)
   IPC_STRUCT_TRAITS_MEMBER(intended_as_new_entry)
   IPC_STRUCT_TRAITS_MEMBER(pending_history_list_offset)
   IPC_STRUCT_TRAITS_MEMBER(current_history_list_offset)
   IPC_STRUCT_TRAITS_MEMBER(current_history_list_length)
@@ skipping 1131 matching lines @@
 // nearest find result in the sending frame.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_GetNearestFindResult_Reply,
                     int /* nfr_request_id */,
                     float /* distance */)
 #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.