Move GLContext creation from //ui/gl to //ui/gl/init.

ui/gl/init/gl_init.gyp

 # Copyright 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
 
   'targets': [
@@ skipping 11 matching lines @@
       ],
       'sources': [
         'gl_initializer.h',
         'gl_initializer_android.cc',
         'gl_initializer_mac.cc',
         'gl_initializer_ozone.cc',
         'gl_initializer_win.cc',
         'gl_initializer_x11.cc',
         'gl_factory.cc',
         'gl_factory.h',
+        'gl_factory_android.cc',
+        'gl_factory_mac.cc',
+        'gl_factory_ozone.cc',
+        'gl_factory_win.cc',
+        'gl_factory_x11.cc',
         'gl_init_export.h',
       ],
       'conditions': [
         ['OS=="mac"', {
           'link_settings': {
             'libraries': [
               '$(SDKROOT)/System/Library/Frameworks/OpenGL.framework',
             ],
           },
         }],
       ],
     },
   ],
 }