Revert of H264 HW encode using MediaFoundation

media/base/win/BUILD.gn

 # 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.
 
 assert(is_win)
 
 component("win") {
   defines = [ "MF_INITIALIZER_IMPLEMENTATION" ]
   set_sources_assignment_filter([])
   sources = [
-    "mf_helpers.cc",
-    "mf_helpers.h",
     "mf_initializer.cc",
     "mf_initializer.h",
     "mf_initializer_export.h",
   ]
   set_sources_assignment_filter(sources_assignment_filter)
   configs += [
     # TODO(jschuh): https://crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
     "//media:media_config",
   ]
   deps = [
     "//base",
     "//media:shared_memory_support",
   ]
   libs = [
     "mf.lib",
     "mfplat.lib",
     "mfreadwrite.lib",
   ]
   ldflags = [
     "/DELAYLOAD:mf.dll",
     "/DELAYLOAD:mfplat.dll",
     "/DELAYLOAD:mfreadwrite.dll",
   ]
 }