Application group identifier should respect ios_app_bundle_id_prefix.

ios/chrome/common/app_group/BUILD.gn

Index: ios/chrome/common/app_group/BUILD.gn
diff --git a/ios/chrome/common/app_group/BUILD.gn b/ios/chrome/common/app_group/BUILD.gn
index 7161f884829245f30f23f86983d6d4376df8e189..735962e478353d3038d3ce5a9fdf3db881071281 100644
--- a/ios/chrome/common/app_group/BUILD.gn
+++ b/ios/chrome/common/app_group/BUILD.gn
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/ios/ios_sdk.gni")
+
 source_set("app_group") {
   sources = [
     "app_group_constants.h",
@@ -14,6 +16,8 @@ source_set("app_group") {
     "//base",
     "//components/version_info",
   ]
+
+  defines = [ "IOS_BUNDLE_ID_PREFIX=\"$ios_app_bundle_id_prefix\"" ]
 }
 
 # This target will be included into application extensions and the list