GN: Make file/dir resolving return errors.

tools/gn/setup.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/setup.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 #include <sstream>
@@ skipping 429 matching lines @@
   }
 
   if (scheduler_.verbose_logging())
     scheduler_.Log("Using source root", FilePathToUTF8(root_path));
   build_settings_.SetRootPath(root_path);
 
   return true;
 }
 
 bool Setup::FillBuildDir(const std::string& build_dir, bool require_exists) {
+  Err err;
   SourceDir resolved =
       SourceDirForCurrentDirectory(build_settings_.root_path()).
-    ResolveRelativeDir(build_dir, build_settings_.root_path_utf8());
-  if (resolved.is_null()) {
-    Err(Location(), "Couldn't resolve build directory.",
-        "The build directory supplied (\"" + build_dir + "\") was not valid.").
-        PrintToStdout();
+    ResolveRelativeDir(Value(nullptr, build_dir), &err,
+        build_settings_.root_path_utf8());
+  if (err.has_error()) {
+    err.PrintToStdout();
     return false;
   }
 
   if (scheduler_.verbose_logging())
     scheduler_.Log("Using build dir", resolved.value());
 
   if (require_exists) {
     base::FilePath build_dir_path = build_settings_.GetFullPath(resolved);
     if (!base::PathExists(build_dir_path.Append(
             FILE_PATH_LITERAL("build.ninja")))) {
@@ skipping 148 matching lines @@
     if (!exec_script_whitelist_value->VerifyTypeIs(Value::LIST, &err)) {
       err.PrintToStdout();
       return false;
     }
     scoped_ptr<std::set<SourceFile>> whitelist(new std::set<SourceFile>);
     for (const auto& item : exec_script_whitelist_value->list_value()) {
       if (!item.VerifyTypeIs(Value::STRING, &err)) {
         err.PrintToStdout();
         return false;
       }
-      whitelist->insert(current_dir.ResolveRelativeFile(item.string_value()));
+      whitelist->insert(current_dir.ResolveRelativeFile(item, &err));
+      if (err.has_error()) {
+        err.PrintToStdout();
+        return false;
+      }
     }
     build_settings_.set_exec_script_whitelist(whitelist.Pass());
   }
 
   return true;
 }