Move Android version stamping from an exec_script -> build rule

chrome/android/BUILD.gn

Index: chrome/android/BUILD.gn
diff --git a/chrome/android/BUILD.gn b/chrome/android/BUILD.gn
index 70a8dec2cc8500833420ce1bb70a442d762e41d4..592ba8729ee5afa73a9243a4fff8190cdfb0b7fa 100644
--- a/chrome/android/BUILD.gn
+++ b/chrome/android/BUILD.gn
@@ -371,19 +371,6 @@ jinja_template("chrome_shell_manifest") {
   output = chrome_shell_manifest
 }
 
-# TODO(cjhopman): This should actually be done as a build step instead of at gn
-# time.
-_version_py_path = "//build/util/version.py"
-_chrome_version_path = "//chrome/VERSION"
-_version_full = exec_script(_version_py_path,
-                            [
-                              "-f",
-                              rebase_path(_chrome_version_path, root_build_dir),
-                              "-t \"@MAJOR@.@MINOR@.@BUILD@.@PATCH@\"",
-                            ],
-                            "value",
-                            [ _chrome_version_path ])
-
 # GYP: //chrome/chrome_shell.gypi:chrome_shell_apk
 android_apk("chrome_shell_apk") {
   testonly = true
@@ -398,7 +385,10 @@ android_apk("chrome_shell_apk") {
   apk_name = "ChromeShell"
   android_manifest = chrome_shell_manifest
   native_libs = [ "libchrome_shell.so" ]
-  native_lib_version_name = _version_full
+  native_lib_version_rule = "//build/util:chrome_version_json"
+  _native_lib_file =
+      rebase_path("$root_gen_dir/CHROME_VERSION.json", root_out_dir)
+  native_lib_version_arg = "@FileArg($_native_lib_file:full-quoted)"
   asset_location = chrome_shell_assets_dir
 
   #TODO(GYP):
@@ -718,7 +708,10 @@ android_apk("chrome_public_apk") {
   android_manifest = android_manifest[1]
   apk_name = "ChromePublic"
   native_libs = [ "$root_build_dir/lib.stripped/libchrome_public.so" ]
-  native_lib_version_name = _version_full
+  native_lib_version_rule = "//build/util:chrome_version_json"
+  _native_lib_file =
+      rebase_path("$root_gen_dir/CHROME_VERSION.json", root_out_dir)
+  native_lib_version_arg = "@FileArg($_native_lib_file:full-quoted)"
   asset_location = chrome_public_apk_assets_dir
 
   deps = [