[Mac/iOS/GN] Document the new rules for create_bundle and runtime_deps.

tools/gn/functions_target.cc

 // Copyright (c) 2013 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.
 
 #include "tools/gn/functions.h"
 
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
@@ skipping 310 matching lines @@
     "  they are computed from all \"bundle_data\" target this one depends on\n"
     "  transitively (the recursion stops at \"create_bundle\" targets).\n"
     "\n"
     "  The \"bundle_*_dir\" properties must be defined. They will be used for\n"
     "  the expansion of {{bundle_*_dir}} rules in \"bundle_data\" outputs.\n"
     "\n"
     "  This target can be used on all platforms though it is designed only to\n"
     "  generate iOS/OS X bundle. In cross-platform projects, it is advised to\n"
     "  put it behind iOS/Mac conditionals.\n"
     "\n"
+    "  If a create_bundle is specified as a data_deps for another target, the\n"
+    "  bundle is considered a leaf, and its public and private dependencies\n"
+    "  will not contribute to any data or data_deps. Required runtime\n"
+    "  dependencies should be placed in the bundle. A create_bundle can\n"
+    "  declare its own explicit data and data_deps, however.\n"
+    "\n"
     "Variables\n"
     "\n"
     "  bundle_root_dir*, bundle_resources_dir*, bundle_executable_dir*,\n"
     "  bundle_plugins_dir*, deps, data_deps, public_deps, visibility,\n"
     "  product_type\n"
     "  * = required\n"
     "\n"
     "Example\n"
     "\n"
     "  # Defines a template to create an application. On most platform, this\n"
@@ skipping 387 matching lines @@
   const Template* templ = scope->GetTemplate(target_type);
   if (templ)
     return templ->Invoke(scope, function, sub_args, block, err);
 
   // Otherwise, assume the target is a built-in target type.
   return ExecuteGenericTarget(target_type.c_str(), scope, function, sub_args,
                               block, err);
 }
 
 }  // namespace functions