[iOS/GN] Add support for info_plist_target to ios_info_plist.

build/config/mac/rules.gni

 # Copyright 2015 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/mac/base_rules.gni")
 
 # Generates Info.plist files for Mac apps and frameworks.
 #
 # Arguments
 #
 #     info_plist:
-#         string, the path to an plist file that will be included in the final
-#         Info.plist generated.
+#         (optional) string, path to the Info.plist file that will be used for
+#         the bundle.
+#
+#     info_plist_target:
+#         (optional) string, if the info_plist is generated from an action,
+#         rather than a regular source file, specify the target name in lieu
+#         of info_plist. The two arguments are mutually exclusive.
 #
 #     executable_name:
 #         string, name of the generated target used for the product
 #         and executable name as specified in the output Info.plist.
 #
 #     extra_substitutions:
 #         (optional) string array, 'key=value' pairs for extra fields which are
 #         specified in a source Info.plist template.
 template("mac_info_plist") {
   assert(defined(invoker.info_plist) != defined(invoker.info_plist_target),
@@ skipping 334 matching lines @@
                            ])
     if (!defined(deps)) {
       deps = []
     }
     deps += [ ":$_loadable_module_bundle_data" ]
 
     bundle_root_dir = "$root_out_dir/$_output_name.plugin/Contents"
     bundle_executable_dir = "$bundle_root_dir/MacOS"
   }
 }