Disable synchronous XMLHttpRequests in platform app documents.

content/common/view_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.
 
 // IPC messages for page rendering.
 // Multiply-included message file, hence no include guard.
 
 #include "base/process.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
@@ skipping 194 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(visual_word_movement_enabled)
   IPC_STRUCT_TRAITS_MEMBER(per_tile_painting_enabled)
   IPC_STRUCT_TRAITS_MEMBER(password_echo_enabled)
   IPC_STRUCT_TRAITS_MEMBER(css_regions_enabled)
   IPC_STRUCT_TRAITS_MEMBER(css_shaders_enabled)
   IPC_STRUCT_TRAITS_MEMBER(default_tile_width)
   IPC_STRUCT_TRAITS_MEMBER(default_tile_height)
   IPC_STRUCT_TRAITS_MEMBER(max_untiled_layer_width)
   IPC_STRUCT_TRAITS_MEMBER(max_untiled_layer_height)
   IPC_STRUCT_TRAITS_MEMBER(fixed_position_creates_stacking_context)
+  IPC_STRUCT_TRAITS_MEMBER(sync_xhr_in_documents_enabled)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(WebMenuItem)
   IPC_STRUCT_TRAITS_MEMBER(label)
   IPC_STRUCT_TRAITS_MEMBER(toolTip)
   IPC_STRUCT_TRAITS_MEMBER(type)
   IPC_STRUCT_TRAITS_MEMBER(action)
   IPC_STRUCT_TRAITS_MEMBER(rtl)
   IPC_STRUCT_TRAITS_MEMBER(has_directional_override)
   IPC_STRUCT_TRAITS_MEMBER(enabled)
@@ skipping 1848 matching lines @@
 // (according to the value of is_hung). The browser can give the user the
 // option of killing the plugin.
 IPC_MESSAGE_ROUTED3(ViewHostMsg_PepperPluginHung,
                     int /* plugin_child_id */,
                     FilePath /* path */,
                     bool /* is_hung */)
 
 // Screen was rotated. Dispatched to the onorientationchange javascript API.
 IPC_MESSAGE_ROUTED1(ViewMsg_OrientationChangeEvent,
                     int /* orientation */)