gn: Support build directories outside the source tree.

tools/gn/function_get_label_info.cc

 // Copyright 2014 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/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/label.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/value.h"
@@ skipping 74 matching lines @@
                       const FunctionCallNode* function,
                       const std::vector<Value>& args,
                       Err* err) {
   if (args.size() != 2) {
     *err = Err(function, "Expected two arguments.");
     return Value();
   }
 
   // Resolve the requested label.
   Label label = Label::Resolve(scope->GetSourceDir(),
-                               ToolchainLabelForScope(scope), args[0], err);
+                               ToolchainLabelForScope(scope), args[0],
+                               scope->settings()->build_settings()->root_path(),
+                               err);
   if (label.is_null())
     return Value();
 
   // Extract the "what" parameter.
   if (!args[1].VerifyTypeIs(Value::STRING, err))
     return Value();
   const std::string& what = args[1].string_value();
 
   Value result(function, Value::STRING);
   if (what == "name") {
@@ skipping 38 matching lines @@
 
   } else {
     *err = Err(args[1], "Unknown value for \"what\" parameter.");
     return Value();
   }
 
   return result;
 }
 
 }  // namespace functions