Remove use_system_skia and skia_system.gypi

skia/skia_system.gypi

-# Copyright 2013 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.
-
-
-# This gypi file contains the shim header generation and other settings to use
-# the system version of skia on Android.
-{
-  'direct_dependent_settings': {
-    # This makes the Android build system set the include path appropriately.
-    'libraries': [ '-lskia' ],
-    # Some Chrome code uses non-public header files (http://crbug.com/274425),
-    # so we need to add this include path for now to make it build. The system
-    # version of skia is already required to be the same as the chromium version
-    # so using the bundled headers shouldn't break anything.
-    'include_dirs': [
-      '../third_party/skia/src/core',
-    ],
-  },
-  'link_settings': {
-    # This actually causes the final binary to be linked against skia.
-    'libraries': [ '-lskia' ],
-  },
-  'variables': {
-    'headers_root_path': '../third_party/skia/include',
-  },
-  'includes': [
-    '../third_party/skia/gyp/public_headers.gypi',
-    '../build/shim_headers.gypi',
-  ],
-}