[iOS][WidgetKit] Extend GN flag to lock beginning of CFBundleVersion

Bug: 1140474
Change-Id: Idc0ee245c51592a6942a80efc508bf96b54df5df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495793Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Auto-Submit: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820824}

ios/chrome/widget_kit_extension/BUILD.gn

@@ -14,6 +14,10 @@ import("//ios/public/provider/chrome/browser/build_config.gni")
 
 tweak_info_plist("tweak_info_plist") {
   info_plist = "Info.plist"
+  # TODO(crbug.com/1140474): Remove once iOS 14.2 reaches mass adoption.
+  if (ios_lock_to_version != "") {
+    args = [ "--lock-to-version=$ios_lock_to_version" ]
+  }
 }
 
 compile_entitlements("entitlements") {