Allow WebRTC to require Mac 10.7 deployments in GN builds.

build/config/mac/mac_sdk.gni

 # 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/chrome_build.gni")
 
+# See https://bugs.chromium.org/p/webrtc/issues/detail?id=5453.
+# We can drop the rtc_require_mac_10_7_deployment flag when Chromium

[Nico, 2016/04/04 18:01:22]

rtc_require_mac_10_7_deployment isn't referenced by anything but this comment.

we're about to bump the deployment target to 10.7 here
https://codereview.chromium.org/1847533004/ and will bump it to 10.9 soon. is
this build_overrides file still needed then? does webrtc keep targeting older os
x versions once chromium stops doing so?

[tkchin_webrtc, 2016/04/04 18:49:01]

We haven't done the work on WebRTC side to fix GN builds for iOS/Mac yet. But
this override is needed to do so (we're using the GYP equivalent).

Afaik there is no reason for us to continue to target old deployment targets if
Chromium is not doing so. I would like very much to be targeting 10.9.

+# also requires a 10.7 deployment target.
+import("//build_overrides/build.gni")
+
 declare_args() {
   # Minimum supported version of the Mac SDK.
   mac_sdk_min = "10.10"
 
   # Minimum supported version of OSX.
-  mac_deployment_target = "10.6"
+  mac_deployment_target = mac_deployment_target_build_override
 
   # Path to a specific version of the Mac SDK, not including a backslash at
   # the end. If empty, the path to the lowest version greater than or equal to
   # mac_sdk_min is used.
   mac_sdk_path = ""
 }
 
 find_sdk_args = [ "--print_sdk_path" ]
 if (is_chrome_branded && is_official_build) {
   find_sdk_args += [
     "--verify",
     mac_sdk_min,
     "--sdk_path=" + mac_sdk_path,
   ]
 } else {
   find_sdk_args += [ mac_sdk_min ]
 }
 
 # The tool will print the SDK path on the first line, and the version on the
 # second line.
 find_sdk_lines =
     exec_script("//build/mac/find_sdk.py", find_sdk_args, "list lines")
 mac_sdk_version = find_sdk_lines[1]
 if (mac_sdk_path == "") {
   mac_sdk_path = find_sdk_lines[0]
 }