Added the command line flag that enables CSS Shaders: "--enable-css-custom-filter".

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(memory_info_enabled)
   IPC_STRUCT_TRAITS_MEMBER(interactive_form_validation_enabled)
   IPC_STRUCT_TRAITS_MEMBER(fullscreen_enabled)
   IPC_STRUCT_TRAITS_MEMBER(allow_displaying_insecure_content)
   IPC_STRUCT_TRAITS_MEMBER(allow_running_insecure_content)
   IPC_STRUCT_TRAITS_MEMBER(enable_scroll_animator)
   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_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 1764 matching lines @@
 // have a javascript send a native value (string, number, boolean) to the
 // listener in Cpp. (DomAutomationController)
 IPC_MESSAGE_ROUTED2(ViewHostMsg_DomOperationResponse,
                     std::string  /* json_string */,
                     int  /* automation_id */)
 
 // Enable or disable inverting of web content pixels, for users who prefer
 // white-on-black.
 IPC_MESSAGE_ROUTED1(ViewMsg_InvertWebContent,
                     bool /* invert */)