Mac/iOS/GN: Generate Info.plist files for Mac apps and frameworks with gn.

build/config/mac/mac_sdk.gni

Index: build/config/mac/mac_sdk.gni
diff --git a/build/config/mac/mac_sdk.gni b/build/config/mac/mac_sdk.gni
index a7aeb38e9276c2f9c681d141bc4ce30c33a21d5e..986bf7942a39342c7f8dbd3d88349b5f56fbe299 100644
--- a/build/config/mac/mac_sdk.gni
+++ b/build/config/mac/mac_sdk.gni
@@ -20,6 +20,9 @@ declare_args() {
   # the end. If empty, the path to the lowest version greater than or equal to
   # mac_sdk_min is used.
   mac_sdk_path = ""
+
+  # The SDK name as accepted by xcodebuild.
+  mac_sdk_name = "macosx"
 }
 
 find_sdk_args = [ "--print_sdk_path" ]
@@ -41,3 +44,10 @@ mac_sdk_version = find_sdk_lines[1]
 if (mac_sdk_path == "") {
   mac_sdk_path = find_sdk_lines[0]
 }
+
+script_name = "//build/config/mac/sdk_info.py"
+_mac_sdk_result = exec_script(script_name, [ mac_sdk_name ], "scope")
+mac_sdk_build = _mac_sdk_result.sdk_build
+xcode_version = _mac_sdk_result.xcode_version
+xcode_build = _mac_sdk_result.xcode_build
+machine_os_build = _mac_sdk_result.machine_os_build