Begin the first small step towards using FilePath everywhere:

base/path_service.cc

 // Copyright (c) 2006-2008 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 "base/path_service.h"
 
 #ifdef OS_WIN
 #include <windows.h>
 #include <shellapi.h>
 #include <shlobj.h>
 #endif
 
+#include "base/file_path.h"
+#include "base/file_util.h"
 #include "base/hash_tables.h"
-#include "base/file_util.h"
 #include "base/lock.h"
 #include "base/logging.h"
 #include "base/singleton.h"
 #include "base/string_util.h"
 
 namespace base {
   bool PathProvider(int key, std::wstring* result);
 #if defined(OS_WIN)
   bool PathProviderWin(int key, std::wstring* result);
 #elif defined(OS_MACOSX)
   bool PathProviderMac(int key, std::wstring* result);
 #elif defined(OS_LINUX)
   bool PathProviderLinux(int key, std::wstring* result);
 #endif
 }
 
 namespace {
 
-typedef base::hash_map<int, std::wstring> PathMap;
+typedef base::hash_map<int, FilePath> PathMap;
 typedef base::hash_set<int> PathSet;
 
 // We keep a linked list of providers.  In a debug build we ensure that no two
 // providers claim overlapping keys.
 struct Provider {
   PathService::ProviderFunc func;
   struct Provider* next;
 #ifndef NDEBUG
   int key_start;
   int key_end;
@@ skipping 76 matching lines @@
 };
   
 static PathData* GetPathData() {
   return Singleton<PathData>::get();
 }
 
 }  // namespace
 
 
 // static
-bool PathService::GetFromCache(int key, std::wstring* result) {
+bool PathService::GetFromCache(int key, FilePath* result) {
   PathData* path_data = GetPathData();
   AutoLock scoped_lock(path_data->lock);
   
   // check for a cached version
   PathMap::const_iterator it = path_data->cache.find(key);
   if (it != path_data->cache.end()) {
     *result = it->second;
     return true;
   }
   return false;
 }
 
 // static
-void PathService::AddToCache(int key, const std::wstring& path) {
+void PathService::AddToCache(int key, const FilePath& path) {
   PathData* path_data = GetPathData();
   AutoLock scoped_lock(path_data->lock);
   // Save the computed path in our cache.
   path_data->cache[key] = path;
 }
 
 // TODO(brettw): this function does not handle long paths (filename > MAX_PATH)
 // characters). This isn't supported very well by Windows right now, so it is
 // moot, but we should keep this in mind for the future.
 // static
-bool PathService::Get(int key, std::wstring* result) {
+bool PathService::Get(int key, FilePath* result) {
   PathData* path_data = GetPathData();
   DCHECK(path_data);
   DCHECK(result);
   DCHECK(key >= base::DIR_CURRENT);
 
   // special case the current directory because it can never be cached
   if (key == base::DIR_CURRENT)
     return file_util::GetCurrentDirectory(result);
 
   if (GetFromCache(key, result))
     return true;
   
-  std::wstring path;
+  std::wstring path_string;
 
   // search providers for the requested path
   // NOTE: it should be safe to iterate here without the lock
   // since RegisterProvider always prepends.
   Provider* provider = path_data->providers;
   while (provider) {
-    if (provider->func(key, &path))
+    if (provider->func(key, &path_string))
       break;
-    DCHECK(path.empty()) << "provider should not have modified path";
+    DCHECK(path_string.empty()) << "provider should not have modified path";
     provider = provider->next;
   }
 
-  if (path.empty())
+  if (path_string.empty())
     return false;
 
+  FilePath path = FilePath::FromWStringHack(path_string);
   AddToCache(key, path);
   
-  result->swap(path);
+  *result = path;
   return true;
 }
 
+// static
+bool PathService::Get(int key, std::wstring* result) {
+  // Deprecated compatibility function.
+  FilePath path;
+  if (!Get(key, &path))
+    return false;
+  *result = path.ToWStringHack();
+  return true;
+}
+
 bool PathService::IsOverridden(int key) {
   PathData* path_data = GetPathData();
   DCHECK(path_data);
 
   AutoLock scoped_lock(path_data->lock);
   return path_data->overrides.find(key) != path_data->overrides.end();
 }
 
 bool PathService::Override(int key, const std::wstring& path) {
   PathData* path_data = GetPathData();
   DCHECK(path_data);
   DCHECK(key > base::DIR_CURRENT) << "invalid path key";
 
   std::wstring file_path = path;
   if (!file_util::AbsolutePath(&file_path))
     return false;
 
   // make sure the directory exists:
   if (!file_util::CreateDirectory(file_path))
     return false;
 
   file_util::TrimTrailingSeparator(&file_path);
 
   AutoLock scoped_lock(path_data->lock);
-  path_data->cache[key] = file_path;
+  path_data->cache[key] = FilePath::FromWStringHack(file_path);
   path_data->overrides.insert(key);
   return true;
 }
 
 bool PathService::SetCurrentDirectory(const std::wstring& current_directory) {
   return file_util::SetCurrentDirectory(current_directory);
 }
 
 void PathService::RegisterProvider(ProviderFunc func, int key_start,
                                    int key_end) {
@@ skipping 17 matching lines @@
   p = new Provider;
   p->is_static = false;
   p->func = func;
   p->next = path_data->providers;
 #ifndef NDEBUG
   p->key_start = key_start;
   p->key_end = key_end;
 #endif
   path_data->providers = p;
 }