Empty overrides file for GN on Mac

R=kjellander@chromium.org

BUG=libyuv:583
TESTED=gn gen out/Debug

Review URL: https://codereview.chromium.org/1870473002 .

build_overrides/build.gni

+# Copyright 2016 The LibYuv 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.
+
+# Using same overrides as WebRTC
+# See https://bugs.chromium.org/p/webrtc/issues/detail?id=5453.
+# Some WebRTC targets require the 10.7 deployment version of the Mac SDK and a
+# 10.11 min SDK but those targets are only used in non-Chromium builds. We can
+# remove this when Chromium drops 10.6 support and also requires 10.7.
+mac_sdk_min_build_override = "10.11"
+mac_deployment_target_build_override = "10.7"

docs/getting_started.md

@@ -184,11 +184,16 @@ Running test with C code:
 
 #### Building with GN
 
-    call gn gen out/Release "--args=is_debug=false target_cpu=\"x86\""
-    call gn gen out/Debug "--args=is_debug=true target_cpu=\"x86\""
+    gn gen out/Release "--args=is_debug=false target_cpu=\"x86\""
+    gn gen out/Debug "--args=is_debug=true target_cpu=\"x86\""
     ninja -C out/Release
     ninja -C out/Debug
 
+### Building Offical with GN
+
+    gn gen out/Official "--args=is_debug=false is_official_build=true is_chrome_branded=true"
+    ninja -C out/Official
+
 ### Linux
 
     GYP_DEFINES="target_arch=x64" ./gyp_libyuv