Fix GN freeze on generating Visual Studio projects

tools/gn/visual_studio_writer_unittest.cc

 // Copyright 2016 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/visual_studio_writer.h"
 
+#include "base/strings/string_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/test_with_scope.h"
 #include "tools/gn/visual_studio_utils.h"
 
 namespace {
 
 class VisualStudioWriterTest : public testing::Test {
  protected:
   TestWithScope setup_;
 };
@@ skipping 76 matching lines @@
   writer.projects_.emplace_back(new VisualStudioWriter::SolutionProject(
       "gn", path, MakeGuid(path, "project"),
       MakeTestPath("/foo/chromium/src/tools/gn"), "Win32"));
 
   path = MakeTestPath(
       "/foo/chromium/src/out/Debug/obj/ABS_PATH/C/foo/bar/bar.vcxproj");
   writer.projects_.emplace_back(new VisualStudioWriter::SolutionProject(
       "bar", path, MakeGuid(path, "project"), MakeTestPath("/foo/bar"),
       "Win32"));
 
+  std::string baz_label_dir_path = MakeTestPath("/foo/bar/baz");
+#if defined(OS_WIN)
+  // Make sure mixed lower and upper-case drive letters are handled properly.
+  baz_label_dir_path[0] = base::ToLowerASCII(baz_label_dir_path[0]);
+#endif
   path = MakeTestPath(
       "/foo/chromium/src/out/Debug/obj/ABS_PATH/C/foo/bar/baz/baz.vcxproj");
   writer.projects_.emplace_back(new VisualStudioWriter::SolutionProject(
-      "baz", path, MakeGuid(path, "project"), MakeTestPath("/foo/bar/baz"),
-      "Win32"));
+      "baz", path, MakeGuid(path, "project"), baz_label_dir_path, "Win32"));
 
   writer.ResolveSolutionFolders();
 
   ASSERT_EQ(MakeTestPath("/foo"), writer.root_folder_path_);
 
   ASSERT_EQ(7u, writer.folders_.size());
 
   ASSERT_EQ("bar", writer.folders_[0]->name);
   ASSERT_EQ(MakeTestPath("/foo/bar"), writer.folders_[0]->path);
   ASSERT_EQ(nullptr, writer.folders_[0]->parent_folder);
@@ skipping 21 matching lines @@
   ASSERT_EQ("gn", writer.folders_[6]->name);
   ASSERT_EQ(MakeTestPath("/foo/chromium/src/tools/gn"),
             writer.folders_[6]->path);
   ASSERT_EQ(writer.folders_[5].get(), writer.folders_[6]->parent_folder);
 
   ASSERT_EQ(writer.folders_[4].get(), writer.projects_[0]->parent_folder);
   ASSERT_EQ(writer.folders_[6].get(), writer.projects_[1]->parent_folder);
   ASSERT_EQ(writer.folders_[0].get(), writer.projects_[2]->parent_folder);
   ASSERT_EQ(writer.folders_[1].get(), writer.projects_[3]->parent_folder);
 }