Enable creation of offscreen contexts which own their backing surface.

gpu/command_buffer/service/service_utils.cc

 // Copyright (c) 2016 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.
 
 #include "gpu/command_buffer/service/service_utils.h"
 
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "gpu/command_buffer/service/gpu_preferences.h"
 
 namespace gpu {
 namespace gles2 {
 
 gl::GLContextAttribs GenerateGLContextAttribs(
     const ContextCreationAttribHelper& attribs_helper,
     const GpuPreferences& gpu_preferences) {
   gl::GLContextAttribs attribs;
   attribs.gpu_preference = attribs_helper.gpu_preference;
   if (gpu_preferences.use_passthrough_cmd_decoder) {
     attribs.bind_generates_resource = attribs_helper.bind_generates_resource;
     attribs.webgl_compatibility_context =
         IsWebGLContextType(attribs_helper.context_type);
   }
+  if (attribs_helper.low_priority) {
+    attribs.low_priority = true;
+  }
   return attribs;
 }
 
 }  // namespace gles2
 }  // namespace gpu