ozone: Create a separate small gfx_ozone target.

ui/gfx/ozone/gfx_ozone.gyp

+# 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.
+
+{
+  'variables': {
+    'chromium_code': 1,
+  },
+  'targets': [{
+    'target_name': 'gfx_ozone',
+    'type': '<(component)',
+    'defines': [
+      'GFX_IMPLEMENTATION',
+    ],
+    'dependencies': [
+      '../../../base/base.gyp:base',
+      '../../../skia/skia.gyp:skia',
+      '../gfx.gyp:gfx_geometry',
+    ],
+    'sources': [
+      'impl/file_surface_factory.cc',
+      'impl/file_surface_factory.h',
+      'surface_factory_ozone.cc',
+      'surface_factory_ozone.h',
+      'surface_ozone_egl.h',
+      'surface_ozone_canvas.h',
+      'overlay_candidates_ozone.cc',
+      'overlay_candidates_ozone.h',
+    ],
+  }],
+}