Move last of platform dependent init from //ui/gl to //ui/gl/init.

ui/gl/gl.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
 
   'targets': [
@@ skipping 63 matching lines @@
         'gl_image_memory.cc',
         'gl_image_memory.h',
         'gl_image_ref_counted_memory.cc',
         'gl_image_ref_counted_memory.h',
         'gl_image_shared_memory.cc',
         'gl_image_shared_memory.h',
         'gl_image_stub.cc',
         'gl_image_stub.h',
         'gl_implementation.cc',
         'gl_implementation.h',
-        'gl_implementation_android.cc',
-        'gl_implementation_mac.cc',
-        'gl_implementation_ozone.cc',
-        'gl_implementation_win.cc',
-        'gl_implementation_x11.cc',
         'gl_osmesa_api_implementation.cc',
         'gl_osmesa_api_implementation.h',
         'gl_share_group.cc',
         'gl_share_group.h',
         'gl_state_restorer.cc',
         'gl_state_restorer.h',
         'gl_surface.cc',
         'gl_surface.h',
         'gl_surface_osmesa.cc',
         'gl_surface_osmesa.h',
@@ skipping 271 matching lines @@
           ],
           'variables': {
             'jni_gen_package': 'ui/gl',
           },
           'includes': [ '../../build/jni_generator.gypi' ],
         },
       ],
     }],
   ],
 }