Remove pepper_messages.h.

content/common/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//content/common/common.gni")
 import("//media/media_options.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 if (is_mac) {
@@ skipping 143 matching lines @@
   } else {
     sources -= [ "font_list_pango.cc" ]
   }
 
   if (enable_plugins) {
     deps += [ "//ppapi/shared_impl" ]
   } else {
     sources -= [
       "pepper_file_util.cc",
       "pepper_file_util.h",
-      "pepper_messages.h",
       "pepper_plugin_list.cc",
       "pepper_plugin_list.h",
       "pepper_renderer_instance_data.cc",
       "pepper_renderer_instance_data.h",
       "plugin_list.cc",
       "plugin_list.h",
     ]
   }
 
   if (!is_win || !use_aura) {
@@ skipping 61 matching lines @@
   public_deps = [
     "//components/leveldb/public/interfaces",
     "//components/mus/public/interfaces",
     "//services/shell/public/interfaces",
     "//skia/public/interfaces",
     "//third_party/WebKit/public:mojo_bindings",
     "//ui/gfx/geometry/mojo",
     "//url/mojo:url_mojom_origin",
   ]
 }