Add a [rtc_]build_with_neon variable to unify conditions.

webrtc/build/webrtc.gni

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
@@ skipping 87 matching lines @@
   }
 
   # TODO(ljubomir): Unset rtc_use_openmax_dl for mips64el once mips64el gets
   # supported in GN (since openmax_dl is not supported for mips64el).
   if (!is_ios && (current_cpu != "arm" || arm_version >= 7)) {
     rtc_use_openmax_dl = true
   } else {
     rtc_use_openmax_dl = false
   }
 
-  # WebRTC builds ARM v7 Neon instruction set optimized code for both iOS and
-  # Android, which is why we currently cannot use the variables in
-  # //build/config/arm.gni (since it disables Neon for Android).
-  rtc_build_armv7_neon = current_cpu == "arm" && arm_version >= 7
+  # Determines whether NEON code will be built. It might not be selected at

[kjellander_webrtc, 2015/06/18 09:06:23]

Same comment update as in common.gypi...

[Andrew MacDonald, 2015/06/25 01:09:09]

Done.

+  # run-time.
+  rtc_build_with_neon = (current_cpu == "arm" &&
+                         (arm_use_neon == 1 || arm_optionally_use_neon == 1)) ||
+                        current_cpu == "arm64"
 }
 
 # Make it possible to provide custom locations for some libraries (move these
 # up into declare_args should we need to actually use them for the GN build).
 rtc_libvpx_dir = "//third_party/libvpx"
 rtc_libyuv_dir = "//third_party/libyuv"
 rtc_opus_dir = "//third_party/opus"