Update from https://crrev.com/320931

gpu/config/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")
 
 declare_args() {
   # Use the PCI lib to collect GPU information on Linux.
   use_libpci = true
 }
@@ skipping 27 matching lines @@
     "gpu_performance_stats.h",
     "gpu_test_config.cc",
     "gpu_test_config.h",
     "gpu_test_expectations_parser.cc",
     "gpu_test_expectations_parser.h",
     "gpu_util.cc",
     "gpu_util.h",
     "software_rendering_list_json.cc",
   ]
 
-  # TODO(jschuh): size_t to int.
-  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
-
-  defines = [ "GPU_IMPLEMENTATION" ]
+  configs += [
+    # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
+    "//build/config/compiler:no_size_t_to_int_warning",
+    "//gpu:gpu_implementation",
+  ]
 
   deps = [
     "//base",
     "//third_party/re2",
     "//ui/gl",
   ]
 
   # Prefer mesa GL headers to system headers, which cause problems on Win.
   include_dirs = [ "//third_party/mesa/src/include" ]
 
   if (is_win) {
     deps += [ "//third_party/libxml" ]
     libs = [
       "dxguid.lib",
       "setupapi.lib",
     ]
 
     if (is_chrome_branded && is_official_build) {
       sources += [
         "//third_party/amd/AmdCfxPxExt.h",
         "//third_party/amd/amd_videocard_info_win.cc",
       ]
     }
   }
   if (use_libpci) {
-    defines += [ "USE_LIBPCI=1" ]
+    defines = [ "USE_LIBPCI=1" ]
   }
   if (is_linux && use_libpci && (use_x11 || use_ozone)) {
     deps += [ "//build/config/linux:libpci" ]
   }
   if (is_linux && use_x11) {
     configs += [
       "//build/config/linux:x11",
       "//build/config/linux:xext",
     ]
     deps += [
       "//third_party/libXNVCtrl",
       "//ui/gfx/x",
     ]
   } else {
     sources -= [ "gpu_info_collector_x11.cc" ]
   }
   if (!use_ozone) {
     sources -= [ "gpu_info_collector_ozone.cc" ]
   }
 }