Fix GN freeze on generating Visual Studio projects

tools/gn/visual_studio_writer.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 <algorithm>
 #include <iterator>
 #include <map>
 #include <memory>
@@ skipping 163 matching lines @@
 VisualStudioWriter::SolutionEntry::~SolutionEntry() = default;
 
 VisualStudioWriter::SolutionProject::SolutionProject(
     const std::string& _name,
     const std::string& _path,
     const std::string& _guid,
     const std::string& _label_dir_path,
     const std::string& _config_platform)
     : SolutionEntry(_name, _path, _guid),
       label_dir_path(_label_dir_path),
-      config_platform(_config_platform) {}
+      config_platform(_config_platform) {
+  // Make sure all paths use the same drive letter case. This is especially
+  // important when searching for the common path prefix.
+  label_dir_path[0] = base::ToUpperASCII(label_dir_path[0]);
+}
 
 VisualStudioWriter::SolutionProject::~SolutionProject() = default;
 
 VisualStudioWriter::VisualStudioWriter(const BuildSettings* build_settings,
                                        const char* config_platform,
                                        Version version)
     : build_settings_(build_settings),
       config_platform_(config_platform),
       ninja_path_output_(build_settings->build_dir(),
                          build_settings->root_path_utf8(),
@@ skipping 605 matching lines @@
   }
 }
 
 std::string VisualStudioWriter::GetNinjaTarget(const Target* target) {
   std::ostringstream ninja_target_out;
   DCHECK(!target->dependency_output_file().value().empty());
   ninja_path_output_.WriteFile(ninja_target_out,
                                target->dependency_output_file());
   return ninja_target_out.str();
 }