Forward bundle product_type to the compile_xcassets tool.

tools/gn/function_toolchain.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 <algorithm>
 #include <limits>
 #include <utility>
 
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
@@ skipping 840 matching lines @@
     "  The copy_bundle_data and compile_xcassets tools only allows the common\n"
     "  tool substitutions. Both tools are required to create iOS/OS X bundles\n"
     "  and need only be defined on those platforms.\n"
     "\n"
     "  The copy_bundle_data tool will be called with one source and needs to\n"
     "  copy (optionally optimizing the data representation) to its output. It\n"
     "  may be called with a directory as input and it needs to be recursively\n"
     "  copied.\n"
     "\n"
     "  The compile_xcassets tool will be called with one or more source (each\n"
-    "  an asset catalog) that needs to be compiled to a single output.\n"
+    "  an asset catalog) that needs to be compiled to a single output. The\n"
+    "  following substitutions are avaiable:\n"
+    "\n"
+    "    {{inputs}}\n"
+    "        Expands to the list of .xcassets to use as input to compile the\n"
+    "        asset catalog.\n"
+    "\n"
+    "    {{bundle_product_type}}\n"
+    "        Expands to the product_type of the bundle that will contain the\n"
+    "        compiled asset catalog. Usually correspond to the product_type\n"

[brettw, 2016/08/11 23:46:35]

Grammar: "correspond" -> "corresponds"

[sdefresne, 2016/08/12 19:38:53]

Done.

+    "        property of the corresponding create_bundle target.\n"
     "\n"
     "Separate linking and dependencies for shared libraries\n"
     "\n"
     "  Shared libraries are special in that not all changes to them require\n"
     "  that dependent targets be re-linked. If the shared library is changed\n"
     "  but no imports or exports are different, dependent code needn't be\n"
     "  relinked, which can speed up the build.\n"
     "\n"
     "  If your link step can output a list of exports from a shared library\n"
     "  and writes the file only if the new one is different, the timestamp of\n"
@@ skipping 206 matching lines @@
   if (err->has_error())
     return Value();
 
   block_scope->DetachFromContaining();
   scope->SetValue("toolchain_args", Value(function, std::move(block_scope)),
                   function);
   return Value();
 }
 
 }  // namespace functions