Move ENABLE_HIDPI to new build flags system

build/config/BUILD.gn

 # Copyright (c) 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.
 
 import("//build/config/allocator.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ skipping 210 matching lines @@
   }
   if (enable_service_discovery) {
     defines += [ "ENABLE_SERVICE_DISCOVERY=1" ]
   }
   if (enable_autofill_dialog) {
     defines += [ "ENABLE_AUTOFILL_DIALOG=1" ]
   }
   if (enable_image_loader_extension) {
     defines += [ "IMAGE_LOADER_EXTENSION=1" ]
   }
-  if (enable_hidpi) {
-    defines += [ "ENABLE_HIDPI=1" ]
-  }
   if (enable_topchrome_md) {
     defines += [ "ENABLE_TOPCHROME_MD=1" ]
   }
   if (enable_wayland_server) {
     defines += [ "ENABLE_WAYLAND_SERVER=1" ]
   }
   if (enable_wifi_display) {
     defines += [ "ENABLE_WIFI_DISPLAY=1" ]
   }
   if (proprietary_codecs) {
@@ skipping 237 matching lines @@
     # This error doesn't happen every time. In VS2013, it seems if the .pch
     # file doesn't exist, no error will be generated (probably MS tested this
     # case but forgot the other one?). To reproduce this error, do a build,
     # then delete the precompile.c.obj file, then build again.
     cflags_c = [ "/wd4206" ]
   } else if (is_mac && !is_official_build && !use_goma) {
     precompiled_header = "build/precompile.h"
     precompiled_source = "//build/precompile.h"
   }
 }