Synchronize GN build configuration with Chrome

mojo/gles2/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("//testing/test.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 
 config("mojo_use_gles2") {
   defines = [ "MOJO_USE_GLES2_IMPL" ]
 }
@@ skipping 10 matching lines @@
     "control_thunks_impl.h",
     "gles2_context.cc",
     "gles2_context.h",
   ]
 
   deps = [
     "//base",
     "//mojo/public/c/system",
     "//gpu/command_buffer/client",
     "//gpu/command_buffer/client:gles2_cmd_helper",
+    "//gpu/command_buffer/client:gles2_cmd_helper_sources",
     "//gpu/command_buffer/client:gles2_implementation",
     "//gpu/command_buffer/common",
     "//mojo/public/c/gpu:MGL",
     "//mojo/public/c/gpu:MGL_onscreen",
     "//mojo/public/c/gpu:MGL_signal_sync_point",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/system",
     "//services/gles2:lib",
     "//mojo/services/gpu/interfaces",
   ]
@@ skipping 51 matching lines @@
     "//mojo/public/c/gpu:MGL",
     "//mojo/public/c/test_support:test_support",
     "//mojo/public/cpp/environment:standalone",
     "//testing/gtest:gtest",
   ]
 
   sources = [
     "mgl_unittest.cc",
   ]
 }