Improve error messages and reporting in GN

tools/gn/loader_unittest.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 <map>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/memory/linked_ptr.h"
@@ skipping 128 matching lines @@
 
   // The default toolchain needs to be set by the build config file.
   mock_ifm_.AddCannedResponse(build_config,
                               "set_default_toolchain(\"//tc:tc\")");
 
   loader->set_async_load_file(mock_ifm_.GetCallback());
 
   // Request the root build file be loaded. This should kick off the default
   // build config loading.
   SourceFile root_build("//BUILD.gn");
-  loader->Load(root_build, Label());
+  loader->Load(root_build, LocationRange(), Label());
   EXPECT_TRUE(mock_ifm_.HasOnePending(build_config));
 
   // Completing the build config load should kick off the root build file load.
   mock_ifm_.IssueAllPending();
   scheduler_.main_loop()->RunUntilIdle();
   EXPECT_TRUE(mock_ifm_.HasOnePending(root_build));
 
   // Load the root build file.
   mock_ifm_.IssueAllPending();
   scheduler_.main_loop()->RunUntilIdle();
 
   // Schedule some other file to load in another toolchain.
   Label second_tc(SourceDir("//tc2/"), "tc2");
   SourceFile second_file("//foo/BUILD.gn");
-  loader->Load(second_file, second_tc);
+  loader->Load(second_file, LocationRange(), second_tc);
   EXPECT_TRUE(mock_ifm_.HasOnePending(SourceFile("//tc2/BUILD.gn")));
 
   // Running the toolchain file should schedule the build config file to load
   // for that toolchain.
   mock_ifm_.IssueAllPending();
   scheduler_.main_loop()->RunUntilIdle();
 
   // We have to tell it we have a toolchain definition now (normally the
   // builder would do this).
   const Settings* default_settings = loader->GetToolchainSettings(Label());
   Toolchain second_tc_object(default_settings, second_tc);
   loader->ToolchainLoaded(&second_tc_object);
   EXPECT_TRUE(mock_ifm_.HasOnePending(build_config));
 
   // Scheduling a second file to load in that toolchain should not make it
   // pending yet (it's waiting for the build config).
   SourceFile third_file("//bar/BUILD.gn");
-  loader->Load(third_file, second_tc);
+  loader->Load(third_file, LocationRange(), second_tc);
   EXPECT_TRUE(mock_ifm_.HasOnePending(build_config));
 
   // Running the build config file should make our third file pending.
   mock_ifm_.IssueAllPending();
   scheduler_.main_loop()->RunUntilIdle();
   EXPECT_TRUE(mock_ifm_.HasTwoPending(second_file, third_file));
 
   EXPECT_FALSE(scheduler_.is_failed());
 }