Revert of command_buffer_gles2: Implement EGL default Display as a global object

gpu/gles2_conform_support/egl/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.
 
 # GYP version: gpu/gles2_conform_support/gles_conform_support.gyp:egl_native
 source_set("egl") {
   output_name = "egl_native"
   sources = [
     "config.cc",
     "config.h",
-    "context.cc",
-    "context.h",
     "display.cc",
     "display.h",
     "egl.cc",
     "surface.cc",
     "surface.h",
-    "test_support.cc",
-    "test_support.h",
-    "thread_state.cc",
-    "thread_state.h",
   ]
 
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   defines = [
     "EGLAPI=",
     "EGLAPIENTRY=",
   ]
 
   deps = [
     "//base",
     "//gpu",
     "//gpu:command_buffer_gles2",
     "//gpu/command_buffer/client:gles2_c_lib_nocheck",
     "//gpu/command_buffer/client:gles2_implementation_no_check",
-    "//gpu/command_buffer/common:gles2_utils",
     "//gpu/command_buffer/service",
     "//ui/base",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 }