Make it possible to switch between two different versions of ANGLE.

gpu/command_buffer_service.gypi

 # 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.
 
 {
   'include_dirs': [
     '..',
   ],
   'all_dependent_settings': {
     'include_dirs': [
       '..',
     ],
   },
   'dependencies': [
     '../base/base.gyp:base',
     '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
     '../crypto/crypto.gyp:crypto',
     '../ui/gl/gl.gyp:gl',
     '../ui/surface/surface.gyp:surface',
     '../ui/ui.gyp:ui',
-    '../third_party/angle/src/build_angle.gyp:translator_glsl',
+    '<(angle_path)/src/build_angle.gyp:translator_glsl',
     '../third_party/khronos/khronos.gyp:khronos_headers',
     '../third_party/protobuf/protobuf.gyp:protobuf_lite',
     '../third_party/smhasher/smhasher.gyp:cityhash',
     '../third_party/re2/re2.gyp:re2',
   ],
   'sources': [
     'command_buffer/service/async_pixel_transfer_delegate.cc',
     'command_buffer/service/async_pixel_transfer_delegate.h',
     'command_buffer/service/async_pixel_transfer_manager_android.cc',
     'command_buffer/service/async_pixel_transfer_manager_idle.cc',
@@ skipping 103 matching lines @@
       ],
     }],
     ['OS in ("win", "android") or (OS == "linux" and use_x11 == 1)', {
       'sources': [
         'command_buffer/service/async_pixel_transfer_manager_egl.cc',
         'command_buffer/service/async_pixel_transfer_manager_egl.h',
       ],
     }]
   ],
 }