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

ui/gl/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("//build/config/ui.gni")
 import("//testing/test.gni")
 
 use_egl = is_win || is_android || is_linux
 use_glx = use_x11
 
@@ skipping 28 matching lines @@
     "android/surface_texture_listener.cc",
     "android/surface_texture_listener.h",
     "gl_bindings.cc",
     "gl_bindings.h",
     "gl_bindings_autogen_gl.cc",
     "gl_bindings_autogen_gl.h",
     "gl_bindings_autogen_osmesa.cc",
     "gl_bindings_autogen_osmesa.h",
     "gl_context.cc",
     "gl_context.h",
-    "gl_context_android.cc",
-    "gl_context_mac.mm",
     "gl_context_osmesa.cc",
     "gl_context_osmesa.h",
     "gl_context_stub.cc",
     "gl_context_stub.h",
     "gl_context_stub_with_extensions.cc",
     "gl_context_stub_with_extensions.h",
-    "gl_context_win.cc",
     "gl_enums.cc",
     "gl_enums.h",
     "gl_enums_implementation_autogen.h",
     "gl_export.h",
     "gl_fence.cc",
     "gl_fence.h",
     "gl_fence_arb.cc",
     "gl_fence_arb.h",
     "gl_fence_nv.cc",
     "gl_fence_nv.h",
@@ skipping 96 matching lines @@
     ]
   }
   if (is_android || is_linux) {
     sources += [
       "gl_implementation_osmesa.cc",
       "gl_implementation_osmesa.h",
     ]
   }
   if (use_x11) {
     sources += [
-      "gl_context_x11.cc",
       "gl_implementation_x11.cc",
       "gl_surface_egl_x11.cc",
       "gl_surface_egl_x11.h",
       "gl_surface_osmesa_x11.cc",
       "gl_surface_osmesa_x11.h",
       "gl_surface_x11.cc",
     ]
 
     data_deps = [
       "//third_party/angle:libEGL",
       "//third_party/angle:libGLESv2",
     ]
   }
   if (use_ozone) {
     sources += [
-      "gl_context_ozone.cc",
       "gl_image_ozone_native_pixmap.cc",
       "gl_image_ozone_native_pixmap.h",
       "gl_implementation_ozone.cc",
       "gl_surface_ozone.cc",
     ]
 
     deps += [ "//ui/ozone" ]
   }
   if (use_glx) {
     sources += [
@@ skipping 199 matching lines @@
     sources = [
       "../android/java/src/org/chromium/ui/gl/SurfaceTextureListener.java",
       "../android/java/src/org/chromium/ui/gl/SurfaceTexturePlatformWrapper.java",
     ]
     public_deps = [
       ":surface_jni_headers",
     ]
     jni_package = "ui/gl"
   }
 }