installer: clean up to use FilePath instead of std::wstring.

BUG=24672
TEST=installer_util_unittests and setup_unittests

Review URL: http://codereview.chromium.org/385129
Patch from Thiago Farina <thiago.farina@gmail.com>.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@32811 0039d316-1c4b-4281-b951-d872f2087c98

26 files changed, 348 insertions, 376 deletions

diff --git a/chrome/installer/setup/install.cc b/chrome/installer/setup/install.cc
index 143f5ba..12273f9 100644
--- a/chrome/installer/setup/install.cc
+++ b/chrome/installer/setup/install.cc
@@ -37,13 +37,6 @@ COMPILE_ASSERT(kNumDllsToRegister > 0,
 
 namespace {
 
-std::wstring AppendPath(const std::wstring& parent_path,
-                        const std::wstring& path) {
-  std::wstring new_path(parent_path);
-  file_util::AppendToPath(&new_path, path);
-  return new_path;
-}
-
 void AddChromeToMediaPlayerList() {
   std::wstring reg_path(installer::kMediaPlayerRegPath);
   // registry paths can also be appended like file system path
@@ -57,24 +50,19 @@ void AddChromeToMediaPlayerList() {
     LOG(ERROR) << "Could not add Chrome to media player inclusion list.";
 }
 
-void AddInstallerCopyTasks(const std::wstring& exe_path,
-                           const std::wstring& archive_path,
-                           const std::wstring& temp_path,
-                           const std::wstring& install_path,
+void AddInstallerCopyTasks(const FilePath& exe_path,
+                           const FilePath& archive_path,
+                           const FilePath& temp_path,
+                           const FilePath& install_path,
                            const std::wstring& new_version,
                            WorkItemList* install_list,
                            bool system_level) {
-  std::wstring installer_dir(installer::GetInstallerPathUnderChrome(
-      install_path, new_version));
-  install_list->AddCreateDirWorkItem(
-      FilePath::FromWStringHack(installer_dir));
-
-  std::wstring exe_dst(installer_dir);
-  std::wstring archive_dst(installer_dir);
-  file_util::AppendToPath(&exe_dst,
-      file_util::GetFilenameFromPath(exe_path));
-  file_util::AppendToPath(&archive_dst,
-      file_util::GetFilenameFromPath(archive_path));
+  FilePath installer_dir(installer::GetInstallerPathUnderChrome(install_path,
+                                                                new_version));
+  install_list->AddCreateDirWorkItem(installer_dir);
+
+  FilePath exe_dst(installer_dir.Append(exe_path.BaseName()));
+  FilePath archive_dst(installer_dir.Append(archive_path.BaseName()));
 
   install_list->AddCopyTreeWorkItem(exe_path, exe_dst, temp_path,
                                     WorkItem::ALWAYS);
@@ -117,16 +105,15 @@ void AppendUninstallCommandLineFlags(std::wstring* uninstall_cmd_line,
 // This method adds work items to create (or update) Chrome uninstall entry in
 // Control Panel->Add/Remove Programs list.
 void AddUninstallShortcutWorkItems(HKEY reg_root,
-                                   const std::wstring& exe_path,
-                                   const std::wstring& install_path,
+                                   const FilePath& exe_path,
+                                   const FilePath& install_path,
                                    const std::wstring& product_name,
                                    const std::wstring& new_version,
                                    WorkItemList* install_list) {
   std::wstring uninstall_cmd(L"\"");
   uninstall_cmd.append(installer::GetInstallerPathUnderChrome(install_path,
-                                                              new_version));
-  file_util::AppendToPath(&uninstall_cmd,
-                          file_util::GetFilenameFromPath(exe_path));
+      new_version).value());
+  file_util::AppendToPath(&uninstall_cmd, exe_path.BaseName().value());
   uninstall_cmd.append(L"\"");
 
   AppendUninstallCommandLineFlags(&uninstall_cmd,
@@ -144,11 +131,12 @@ void AddUninstallShortcutWorkItems(HKEY reg_root,
                                        uninstall_cmd, true);
   install_list->AddSetRegValueWorkItem(reg_root,
                                        uninstall_reg,
-                                       L"InstallLocation", install_path, true);
+                                       L"InstallLocation",
+                                       install_path.value(), true);
 
   // DisplayIcon, NoModify and NoRepair
-  std::wstring chrome_icon = AppendPath(install_path,
-                                        installer_util::kChromeExe);
+  std::wstring chrome_icon = install_path.Append(
+      installer_util::kChromeExe).value();
   ShellUtil::GetChromeIcon(chrome_icon);
   install_list->AddSetRegValueWorkItem(reg_root, uninstall_reg,
                                        L"DisplayIcon", chrome_icon, true);
@@ -180,14 +168,11 @@ void AddUninstallShortcutWorkItems(HKEY reg_root,
 // as chrome.exe so Chrome first run can find it. This function will be called
 // only on the first install of Chrome.
 void CopyPreferenceFileForFirstRun(bool system_level,
-                                   const std::wstring& prefs_source_path) {
-  FilePath prefs_dest_path = FilePath::FromWStringHack(
-      installer::GetChromeInstallPath(system_level));
+                                   const FilePath& prefs_source_path) {
+  FilePath prefs_dest_path = installer::GetChromeInstallPath(system_level);
   prefs_dest_path = prefs_dest_path.Append(installer_util::kDefaultMasterPrefs);
-  if (!file_util::CopyFile(FilePath::FromWStringHack(prefs_source_path),
-                           prefs_dest_path)) {
+  if (!file_util::CopyFile(prefs_source_path, prefs_dest_path))
     LOG(INFO) << "Failed to copy master preferences.";
-  }
 }
 
 // This method creates Chrome shortcuts in Start->Programs for all users or
@@ -204,8 +189,8 @@ void CopyPreferenceFileForFirstRun(bool system_level,
 //
 // If the shortcuts do not exist, the function does not recreate them during
 // update.
-bool CreateOrUpdateChromeShortcuts(const std::wstring& exe_path,
-                                   const std::wstring& install_path,
+bool CreateOrUpdateChromeShortcuts(const FilePath& exe_path,
+                                   const FilePath& install_path,
                                    const std::wstring& new_version,
                                    installer_util::InstallStatus install_status,
                                    bool system_install,
@@ -233,53 +218,52 @@ bool CreateOrUpdateChromeShortcuts(const std::wstring& exe_path,
   //   shortcuts since our install. So on updates we only update if shortcut
   //   already exists)
   bool ret = true;
-  FilePath chrome_link(shortcut_path);  // Chrome link (launches Chrome)
-  chrome_link = chrome_link.Append(product_name + L".lnk");
-  std::wstring chrome_exe(install_path);  // Chrome link target
-  file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
+  // Chrome link (launches Chrome).
+  FilePath chrome_link(shortcut_path.Append(product_name + L".lnk"));
+  // Chrome link target.
+  FilePath chrome_exe(install_path.Append(installer_util::kChromeExe));
 
   if ((install_status == installer_util::FIRST_INSTALL_SUCCESS) ||
       (install_status == installer_util::INSTALL_REPAIRED)) {
     if (!file_util::PathExists(shortcut_path))
-      file_util::CreateDirectoryW(shortcut_path);
+      file_util::CreateDirectory(shortcut_path);
 
-    LOG(INFO) << "Creating shortcut to " << chrome_exe << " at "
+    LOG(INFO) << "Creating shortcut to " << chrome_exe.value() << " at "
               << chrome_link.value();
-    ret = ret && ShellUtil::UpdateChromeShortcut(chrome_exe,
+    ret = ret && ShellUtil::UpdateChromeShortcut(chrome_exe.value(),
                                                  chrome_link.value(),
                                                  product_desc, true);
   } else if (file_util::PathExists(chrome_link)) {
     LOG(INFO) << "Updating shortcut at " << chrome_link.value()
-              << " to point to " << chrome_exe;
-    ret = ret && ShellUtil::UpdateChromeShortcut(chrome_exe,
+              << " to point to " << chrome_exe.value();
+    ret = ret && ShellUtil::UpdateChromeShortcut(chrome_exe.value(),
                                                  chrome_link.value(),
                                                  product_desc, false);
   }
 
-  // Create/update uninstall link
-  FilePath uninstall_link(shortcut_path);  // Uninstall Chrome link
-  uninstall_link = uninstall_link.Append(
-      dist->GetUninstallLinkName() + L".lnk");
+  // Create/update uninstall link.
+  FilePath uninstall_link(shortcut_path.Append(
+      dist->GetUninstallLinkName() + L".lnk"));
   if ((install_status == installer_util::FIRST_INSTALL_SUCCESS) ||
       (install_status == installer_util::INSTALL_REPAIRED) ||
       (file_util::PathExists(uninstall_link))) {
     if (!file_util::PathExists(shortcut_path))
-      file_util::CreateDirectoryW(shortcut_path);
-    std::wstring setup_exe(installer::GetInstallerPathUnderChrome(install_path,
-                                                                  new_version));
-    file_util::AppendToPath(&setup_exe,
-                            file_util::GetFilenameFromPath(exe_path));
+      file_util::CreateDirectory(shortcut_path);
+    FilePath setup_exe(installer::GetInstallerPathUnderChrome(install_path,
+                                                              new_version));
+    setup_exe = setup_exe.Append(exe_path.BaseName());
 
     std::wstring arguments;
     AppendUninstallCommandLineFlags(&arguments, system_install);
 
     LOG(INFO) << "Creating/updating uninstall link at "
               << uninstall_link.value();
-    ret = ret && file_util::CreateShortcutLink(setup_exe.c_str(),
+    ret = ret && file_util::CreateShortcutLink(setup_exe.value().c_str(),
                                                uninstall_link.value().c_str(),
                                                NULL,
                                                arguments.c_str(),
-                                               NULL, setup_exe.c_str(), 0,
+                                               NULL, setup_exe.value().c_str(),
+                                               0,
                                                NULL);
   }
 
@@ -287,16 +271,16 @@ bool CreateOrUpdateChromeShortcuts(const std::wstring& exe_path,
   // is specified we want to create them, otherwise we update them only if
   // they exist.
   if (system_install) {
-    ret = ret && ShellUtil::CreateChromeDesktopShortcut(chrome_exe,
+    ret = ret && ShellUtil::CreateChromeDesktopShortcut(chrome_exe.value(),
         product_desc, ShellUtil::SYSTEM_LEVEL, alt_shortcut,
         create_all_shortcut);
-    ret = ret && ShellUtil::CreateChromeQuickLaunchShortcut(chrome_exe,
+    ret = ret && ShellUtil::CreateChromeQuickLaunchShortcut(chrome_exe.value(),
         ShellUtil::CURRENT_USER | ShellUtil::SYSTEM_LEVEL, create_all_shortcut);
   } else {
-    ret = ret && ShellUtil::CreateChromeDesktopShortcut(chrome_exe,
+    ret = ret && ShellUtil::CreateChromeDesktopShortcut(chrome_exe.value(),
         product_desc, ShellUtil::CURRENT_USER, alt_shortcut,
         create_all_shortcut);
-    ret = ret && ShellUtil::CreateChromeQuickLaunchShortcut(chrome_exe,
+    ret = ret && ShellUtil::CreateChromeQuickLaunchShortcut(chrome_exe.value(),
         ShellUtil::CURRENT_USER, create_all_shortcut);
   }
 
@@ -311,8 +295,8 @@ bool CreateOrUpdateChromeShortcuts(const std::wstring& exe_path,
 // If these operations are successful, the function returns true, otherwise
 // false.
 bool DoPostInstallTasks(HKEY reg_root,
-                        const std::wstring& exe_path,
-                        const std::wstring& install_path,
+                        const FilePath& exe_path,
+                        const FilePath& install_path,
                         const std::wstring& new_chrome_exe,
                         const std::wstring& current_version,
                         const installer::Version& new_version) {
@@ -334,12 +318,13 @@ bool DoPostInstallTasks(HKEY reg_root,
                                        current_version.c_str(),
                                        true);
 
-    std::wstring rename_cmd(installer::GetInstallerPathUnderChrome(
-        install_path, new_version.GetString()));
-    file_util::AppendToPath(&rename_cmd,
-                            file_util::GetFilenameFromPath(exe_path));
-    rename_cmd = L"\"" + rename_cmd +
-                 L"\" --" + installer_util::switches::kRenameChromeExe;
+    FilePath setup_exe_path(installer::GetInstallerPathUnderChrome(install_path,
+        new_version.GetString()));
+    setup_exe_path = setup_exe_path.Append(exe_path.BaseName());
+
+    std::wstring rename_cmd = L"\"" + setup_exe_path.value() +
+        L"\" --" + installer_util::switches::kRenameChromeExe;
+
     if (reg_root == HKEY_LOCAL_MACHINE)
       rename_cmd = rename_cmd + L" --" + installer_util::switches::kSystemLevel;
 
@@ -377,11 +362,12 @@ bool DoPostInstallTasks(HKEY reg_root,
   // Now we need to register any self registering components and unregister
   // any that were left from the old version that is being upgraded:
   if (!current_version.empty()) {
-    std::wstring old_dll_path(install_path);
-    file_util::AppendToPath(&old_dll_path, current_version);
+    FilePath old_dll_path(install_path.Append(current_version));
     scoped_ptr<WorkItemList> old_dll_list(WorkItem::CreateWorkItemList());
-    if (InstallUtil::BuildDLLRegistrationList(old_dll_path, kDllsToRegister,
-                                              kNumDllsToRegister, false,
+    if (InstallUtil::BuildDLLRegistrationList(old_dll_path.value(),
+                                              kDllsToRegister,
+                                              kNumDllsToRegister,
+                                              false,
                                               old_dll_list.get())) {
       // Don't abort the install as a result of a failure to unregister old
       // DLLs.
@@ -389,10 +375,9 @@ bool DoPostInstallTasks(HKEY reg_root,
     }
   }
 
-  std::wstring dll_path(install_path);
-  file_util::AppendToPath(&dll_path, new_version.GetString());
+  FilePath dll_path(install_path.Append(new_version.GetString()));
   scoped_ptr<WorkItemList> dll_list(WorkItem::CreateWorkItemList());
-  if (InstallUtil::BuildDLLRegistrationList(dll_path, kDllsToRegister,
+  if (InstallUtil::BuildDLLRegistrationList(dll_path.value(), kDllsToRegister,
                                             kNumDllsToRegister, true,
                                             dll_list.get())) {
     if (!dll_list->Do()) {
@@ -422,7 +407,7 @@ bool Is64bit() {
   return false;
 }
 
-void RegisterChromeOnMachine(const std::wstring& install_path,
+void RegisterChromeOnMachine(const FilePath& install_path,
                              bool system_level,
                              bool make_chrome_default) {
   // Try to add Chrome to Media Player shim inclusion list. We don't do any
@@ -432,16 +417,15 @@ void RegisterChromeOnMachine(const std::wstring& install_path,
 
   // Is --make-chrome-default option is given we make Chrome default browser
   // otherwise we only register it on the machine as a valid browser.
-  std::wstring chrome_exe(install_path);
-  file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
+  FilePath chrome_exe(install_path.Append(installer_util::kChromeExe));
   LOG(INFO) << "Registering Chrome as browser";
   if (make_chrome_default) {
     int level = ShellUtil::CURRENT_USER;
     if (system_level)
       level = level | ShellUtil::SYSTEM_LEVEL;
-    ShellUtil::MakeChromeDefault(level, chrome_exe, true);
+    ShellUtil::MakeChromeDefault(level, chrome_exe.value(), true);
   } else {
-    ShellUtil::RegisterChromeBrowser(chrome_exe, L"", false);
+    ShellUtil::RegisterChromeBrowser(chrome_exe.value(), L"", false);
   }
 }
 
@@ -470,11 +454,11 @@ void RegisterChromeOnMachine(const std::wstring& install_path,
 // install_path. If install_path does not exist before calling the function
 // (typical new install), the function creates install_path during install
 // and removes the whole directory during rollback.
-bool InstallNewVersion(const std::wstring& exe_path,
-                       const std::wstring& archive_path,
-                       const std::wstring& src_path,
-                       const std::wstring& install_path,
-                       const std::wstring& temp_dir,
+bool InstallNewVersion(const FilePath& exe_path,
+                       const FilePath& archive_path,
+                       const FilePath& src_path,
+                       const FilePath& install_path,
+                       const FilePath& temp_dir,
                        const HKEY reg_root,
                        const installer::Version& new_version,
                        std::wstring* current_version) {
@@ -483,60 +467,59 @@ bool InstallNewVersion(const std::wstring& exe_path,
 
   if (InstallUtil::IsChromeFrameProcess()) {
     // Make sure that we don't end up deleting installed files on next reboot.
-    if (!RemoveFromMovesPendingReboot(install_path.c_str())) {
+    if (!RemoveFromMovesPendingReboot(install_path.value().c_str())) {
       LOG(ERROR) << "Error accessing pending moves value.";
     }
   }
 
   scoped_ptr<WorkItemList> install_list(WorkItem::CreateWorkItemList());
   // A temp directory that work items need and the actual install directory.
-  install_list->AddCreateDirWorkItem(FilePath::FromWStringHack(temp_dir));
-  install_list->AddCreateDirWorkItem(FilePath::FromWStringHack(install_path));
+  install_list->AddCreateDirWorkItem(temp_dir);
+  install_list->AddCreateDirWorkItem(install_path);
 
   // If it is system level install copy the version folder (since we want to
   // take the permissions of %ProgramFiles% folder) otherwise just move it.
   if (reg_root == HKEY_LOCAL_MACHINE) {
     install_list->AddCopyTreeWorkItem(
-        AppendPath(src_path, new_version.GetString()),
-        AppendPath(install_path, new_version.GetString()),
+        src_path.Append(new_version.GetString()),
+        install_path.Append(new_version.GetString()),
         temp_dir, WorkItem::ALWAYS);
   } else {
     install_list->AddMoveTreeWorkItem(
-        AppendPath(src_path, new_version.GetString()),
-        AppendPath(install_path, new_version.GetString()),
+        src_path.Append(new_version.GetString()),
+        install_path.Append(new_version.GetString()),
         temp_dir);
   }
 
   // Delete any new_chrome.exe if present (we will end up creating a new one
   // if required) and then copy chrome.exe
-  std::wstring new_chrome_exe = AppendPath(install_path,
-                                           installer_util::kChromeNewExe);
+  FilePath new_chrome_exe(install_path.Append(installer_util::kChromeNewExe));
   BrowserDistribution* dist = BrowserDistribution::GetDistribution();
   RegKey chrome_key(reg_root, dist->GetVersionKey().c_str(), KEY_READ);
-  if (file_util::PathExists(FilePath::FromWStringHack(new_chrome_exe)))
+  if (file_util::PathExists(new_chrome_exe))
     chrome_key.ReadValue(google_update::kRegOldVersionField, current_version);
   if (current_version->empty())
     chrome_key.ReadValue(google_update::kRegVersionField, current_version);
   chrome_key.Close();
 
-  install_list->AddDeleteTreeWorkItem(new_chrome_exe, std::wstring());
+  install_list->AddDeleteTreeWorkItem(new_chrome_exe, FilePath());
   install_list->AddCopyTreeWorkItem(
-      AppendPath(src_path, installer_util::kChromeExe),
-      AppendPath(install_path, installer_util::kChromeExe),
+      src_path.Append(installer_util::kChromeExe),
+      install_path.Append(installer_util::kChromeExe),
       temp_dir, WorkItem::NEW_NAME_IF_IN_USE, new_chrome_exe);
 
   // Extra executable for 64 bit systems.
   if (Is64bit()) {
     install_list->AddCopyTreeWorkItem(
-        AppendPath(src_path, installer::kWowHelperExe),
-        AppendPath(install_path, installer::kWowHelperExe),
+        src_path.Append(installer::kWowHelperExe),
+        install_path.Append(installer::kWowHelperExe),
         temp_dir, WorkItem::ALWAYS);
   }
 
   // Copy the default Dictionaries only if the folder doesnt exist already
   install_list->AddCopyTreeWorkItem(
-      AppendPath(src_path, installer::kDictionaries),
-      AppendPath(install_path, installer::kDictionaries),
+      src_path.Append(installer::kDictionaries),
+      install_path.Append(installer::kDictionaries),
       temp_dir, WorkItem::IF_NOT_PRESENT);
 
   // Copy installer in install directory and
@@ -550,7 +533,7 @@ bool InstallNewVersion(const std::wstring& exe_path,
 
   // Delete any old_chrome.exe if present.
   install_list->AddDeleteTreeWorkItem(
-      AppendPath(install_path, installer_util::kChromeOldExe), std::wstring());
+      install_path.Append(installer_util::kChromeOldExe), FilePath());
 
   // Create Version key (if not already present) and set the new Chrome
   // version as last step.
@@ -567,7 +550,8 @@ bool InstallNewVersion(const std::wstring& exe_path,
 
   if (!install_list->Do() ||
       !DoPostInstallTasks(reg_root, exe_path, install_path,
-                          new_chrome_exe, *current_version, new_version)) {
+                          new_chrome_exe.value(),
+                          *current_version, new_version)) {
     LOG(ERROR) << "Install failed, rolling back... ";
     install_list->Rollback();
     LOG(ERROR) << "Rollback complete. ";
@@ -579,33 +563,35 @@ bool InstallNewVersion(const std::wstring& exe_path,
 
 }  // namespace
 
-std::wstring installer::GetInstallerPathUnderChrome(
-    const std::wstring& install_path, const std::wstring& new_version) {
-  std::wstring installer_path(install_path);
-  file_util::AppendToPath(&installer_path, new_version);
-  file_util::AppendToPath(&installer_path, installer_util::kInstallerDir);
+FilePath installer::GetInstallerPathUnderChrome(const FilePath& install_path,
+                                                const std::wstring& new_version)
+{
+  FilePath installer_path(install_path.Append(new_version));
+  installer_path = installer_path.Append(installer_util::kInstallerDir);
   return installer_path;
 }
 
 installer_util::InstallStatus installer::InstallOrUpdateChrome(
-    const std::wstring& exe_path, const std::wstring& archive_path,
-    const std::wstring& install_temp_path, const std::wstring& prefs_path,
-    const DictionaryValue* prefs, const Version& new_version,
+    const FilePath& exe_path,
+    const FilePath& archive_path,
+    const FilePath& install_temp_path,
+    const FilePath& prefs_path,
+    const DictionaryValue* prefs,
+    const Version& new_version,
     const Version* installed_version) {
   bool system_install = false;
   installer_util::GetDistroBooleanPreference(prefs,
       installer_util::master_preferences::kSystemLevel, &system_install);
-  std::wstring install_path(GetChromeInstallPath(system_install));
+  FilePath install_path(GetChromeInstallPath(system_install));
   if (install_path.empty()) {
     LOG(ERROR) << "Could not get installation destination path.";
     return installer_util::INSTALL_FAILED;
   } else {
-    LOG(INFO) << "install destination path: " << install_path;
+    LOG(INFO) << "install destination path: " << install_path.value();
   }
 
-  std::wstring src_path(install_temp_path);
-  file_util::AppendToPath(&src_path, std::wstring(kInstallSourceDir));
-  file_util::AppendToPath(&src_path, std::wstring(kInstallSourceChromeDir));
+  FilePath src_path(install_temp_path.Append(kInstallSourceDir));
+  src_path = src_path.Append(kInstallSourceChromeDir);
 
   HKEY reg_root = (system_install) ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
   std::wstring current_version;
@@ -620,7 +606,7 @@ installer_util::InstallStatus installer::InstallOrUpdateChrome(
     if (!installed_version) {
       LOG(INFO) << "First install of version " << new_version.GetString();
       result = installer_util::FIRST_INSTALL_SUCCESS;
-      CopyPreferenceFileForFirstRun(system_install, prefs_path);
+      CopyPreferenceFileForFirstRun(system_install, FilePath(prefs_path));
     } else if (new_version.GetString() == installed_version->GetString()) {
       LOG(INFO) << "Install repaired of version " << new_version.GetString();
       result = installer_util::INSTALL_REPAIRED;
diff --git a/chrome/installer/setup/install.h b/chrome/installer/setup/install.h
index 305819a..8810803 100644
--- a/chrome/installer/setup/install.h
+++ b/chrome/installer/setup/install.h
@@ -12,11 +12,13 @@
 #include "chrome/installer/util/util_constants.h"
 #include "chrome/installer/util/version.h"
 
+class FilePath;
+
 namespace installer {
 // Get path to the installer under Chrome version folder
 // (for example <path>\Google\Chrome\<Version>\installer)
-std::wstring GetInstallerPathUnderChrome(const std::wstring& install_path,
-                                         const std::wstring& new_version);
+FilePath GetInstallerPathUnderChrome(const FilePath& install_path,
+                                     const std::wstring& new_version);
 
 // This function installs or updates a new version of Chrome. It returns
 // install status (failed, new_install, updated etc).
@@ -36,9 +38,12 @@ std::wstring GetInstallerPathUnderChrome(const std::wstring& install_path,
 // Note: since caller unpacks Chrome to install_temp_path\source, the caller
 // is responsible for cleaning up install_temp_path.
 installer_util::InstallStatus InstallOrUpdateChrome(
-    const std::wstring& exe_path, const std::wstring& archive_path,
-    const std::wstring& install_temp_path, const std::wstring& prefs_path,
-    const DictionaryValue* prefs, const Version& new_version,
+    const FilePath& exe_path,
+    const FilePath& archive_path,
+    const FilePath& install_temp_path,
+    const FilePath& prefs_path,
+    const DictionaryValue* prefs,
+    const Version& new_version,
     const Version* installed_version);
 }
 
diff --git a/chrome/installer/setup/setup_main.cc b/chrome/installer/setup/setup_main.cc
index dab45e2..5cfae0d 100644
--- a/chrome/installer/setup/setup_main.cc
+++ b/chrome/installer/setup/setup_main.cc
@@ -51,23 +51,23 @@ namespace {
 // is unpacked in the path specified by parameter "path".
 DWORD UnPackArchive(const std::wstring& archive, bool system_install,
                     const installer::Version* installed_version,
-                    const std::wstring& temp_path, const std::wstring& path,
+                    const FilePath& temp_path, const FilePath& path,
                     bool& incremental_install) {
   // First uncompress the payload. This could be a differential
   // update (patch.7z) or full archive (chrome.7z). If this uncompress fails
   // return with error.
   std::wstring unpacked_file;
-  int32 ret = LzmaUtil::UnPackArchive(archive, temp_path, &unpacked_file);
+  int32 ret = LzmaUtil::UnPackArchive(archive, temp_path.value(),
+                                      &unpacked_file);
   if (ret != NO_ERROR)
     return ret;
 
-  std::wstring uncompressed_archive(temp_path);
-  file_util::AppendToPath(&uncompressed_archive, installer::kChromeArchive);
+  FilePath uncompressed_archive(temp_path.Append(installer::kChromeArchive));
 
   // Check if this is differential update and if it is, patch it to the
   // installer archive that should already be on the machine. We assume
   // it is a differential installer if chrome.7z is not found.
-  if (!file_util::PathExists(FilePath::FromWStringHack(uncompressed_archive))) {
+  if (!file_util::PathExists(uncompressed_archive)) {
     incremental_install = true;
     LOG(INFO) << "Differential patch found. Applying to existing archive.";
     if (!installed_version) {
@@ -75,21 +75,20 @@ DWORD UnPackArchive(const std::wstring& archive, bool system_install,
                  << "installed on the system.";
       return installer_util::CHROME_NOT_INSTALLED;
     }
-    std::wstring existing_archive =
-        installer::GetChromeInstallPath(system_install);
-    file_util::AppendToPath(&existing_archive,
-                            installed_version->GetString());
-    file_util::AppendToPath(&existing_archive, installer_util::kInstallerDir);
-    file_util::AppendToPath(&existing_archive, installer::kChromeArchive);
-    if (int i = setup_util::ApplyDiffPatch(existing_archive, unpacked_file,
-                                           uncompressed_archive)) {
+    FilePath existing_archive(installer::GetChromeInstallPath(system_install));
+    existing_archive = existing_archive.Append(installed_version->GetString());
+    existing_archive = existing_archive.Append(installer_util::kInstallerDir);
+    existing_archive = existing_archive.Append(installer::kChromeArchive);
+    if (int i = setup_util::ApplyDiffPatch(existing_archive.value(),
+        unpacked_file, uncompressed_archive.value())) {
       LOG(ERROR) << "Binary patching failed with error " << i;
       return i;
     }
   }
 
   // Unpack the uncompressed archive.
-  return LzmaUtil::UnPackArchive(uncompressed_archive, path, &unpacked_file);
+  return LzmaUtil::UnPackArchive(uncompressed_archive.value(), path.value(),
+                                 &unpacked_file);
 }
 
 
@@ -99,17 +98,14 @@ DWORD UnPackArchive(const std::wstring& archive, bool system_install,
 // system and a key called 'opv' in the registry. This function will move
 // new_chrome.exe to chrome.exe and delete 'opv' key in one atomic operation.
 installer_util::InstallStatus RenameChromeExecutables(bool system_install) {
-  std::wstring chrome_path(installer::GetChromeInstallPath(system_install));
+  FilePath chrome_path(installer::GetChromeInstallPath(system_install));
 
-  std::wstring chrome_exe(chrome_path);
-  file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
-  std::wstring chrome_old_exe(chrome_path);
-  file_util::AppendToPath(&chrome_old_exe, installer_util::kChromeOldExe);
-  std::wstring chrome_new_exe(chrome_path);
-  file_util::AppendToPath(&chrome_new_exe, installer_util::kChromeNewExe);
+  FilePath chrome_exe(chrome_path.Append(installer_util::kChromeExe));
+  FilePath chrome_old_exe(chrome_path.Append(installer_util::kChromeOldExe));
+  FilePath chrome_new_exe(chrome_path.Append(installer_util::kChromeNewExe));
 
   scoped_ptr<WorkItemList> install_list(WorkItem::CreateWorkItemList());
-  install_list->AddDeleteTreeWorkItem(chrome_old_exe, std::wstring());
+  install_list->AddDeleteTreeWorkItem(chrome_old_exe, FilePath());
   FilePath temp_path;
   if (!file_util::CreateNewTempDirectory(L"chrome_", &temp_path)) {
     LOG(ERROR) << "Failed to create Temp directory " << temp_path.value();
@@ -117,16 +113,16 @@ installer_util::InstallStatus RenameChromeExecutables(bool system_install) {
   }
   install_list->AddCopyTreeWorkItem(chrome_new_exe,
                                     chrome_exe,
-                                    temp_path.ToWStringHack(),
+                                    temp_path,
                                     WorkItem::IF_DIFFERENT,
-                                    std::wstring());
+                                    FilePath());
   HKEY reg_root = system_install ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
   BrowserDistribution *dist = BrowserDistribution::GetDistribution();
   install_list->AddDeleteRegValueWorkItem(reg_root,
                                           dist->GetVersionKey(),
                                           google_update::kRegOldVersionField,
                                           true);
-  install_list->AddDeleteTreeWorkItem(chrome_new_exe, std::wstring());
+  install_list->AddDeleteTreeWorkItem(chrome_new_exe, FilePath());
   install_list->AddDeleteRegValueWorkItem(reg_root,
                                           dist->GetVersionKey(),
                                           google_update::kRegRenameCmdField,
@@ -162,8 +158,7 @@ bool CheckPreInstallConditions(const installer::Version* installed_version,
   // either does not exist or can be deleted (i.e. is not locked by some other
   // process).
   if (!installed_version) {
-    FilePath install_path = FilePath::FromWStringHack(
-        installer::GetChromeInstallPath(system_install));
+    FilePath install_path(installer::GetChromeInstallPath(system_install));
     if (file_util::PathExists(install_path) &&
         !file_util::Delete(install_path, true)) {
       LOG(ERROR) << "Installation directory " << install_path.value()
@@ -214,24 +209,19 @@ installer_util::InstallStatus InstallChrome(const CommandLine& cmd_line,
   LOG(INFO) << "created path " << temp_path.value();
 
   BrowserDistribution* dist = BrowserDistribution::GetDistribution();
-  std::wstring unpack_path(temp_path.ToWStringHack());
-  file_util::AppendToPath(&unpack_path,
-                          std::wstring(installer::kInstallSourceDir));
+  FilePath unpack_path(temp_path.Append(installer::kInstallSourceDir));
   bool incremental_install = false;
   if (UnPackArchive(archive, system_level, installed_version,
-                    temp_path.ToWStringHack(), unpack_path,
-                    incremental_install)) {
+                    temp_path, unpack_path, incremental_install)) {
     install_status = installer_util::UNCOMPRESSION_FAILED;
     InstallUtil::WriteInstallerResult(system_level, install_status,
                                       IDS_INSTALL_UNCOMPRESSION_FAILED_BASE,
                                       NULL);
   } else {
-    LOG(INFO) << "unpacked to " << unpack_path;
-    std::wstring src_path(unpack_path);
-    file_util::AppendToPath(&src_path,
-        std::wstring(installer::kInstallSourceChromeDir));
+    LOG(INFO) << "unpacked to " << unpack_path.value();
+    FilePath src_path(unpack_path.Append(installer::kInstallSourceChromeDir));
     scoped_ptr<installer::Version>
-        installer_version(setup_util::GetVersionFromDir(src_path));
+        installer_version(setup_util::GetVersionFromDir(src_path.value()));
     if (!installer_version.get()) {
       LOG(ERROR) << "Did not find any valid version in installer.";
       install_status = installer_util::INVALID_ARCHIVE;
@@ -249,19 +239,17 @@ installer_util::InstallStatus InstallChrome(const CommandLine& cmd_line,
       } else {
         // We want to keep uncompressed archive (chrome.7z) that we get after
         // uncompressing and binary patching. Get the location for this file.
-        std::wstring archive_to_copy(temp_path.ToWStringHack());
-        file_util::AppendToPath(&archive_to_copy,
-                                std::wstring(installer::kChromeArchive));
-        std::wstring prefs_source_path = cmd_line.GetSwitchValue(
-            installer_util::switches::kInstallerData);
+        FilePath archive_to_copy(temp_path.Append(installer::kChromeArchive));
+        FilePath prefs_source_path = cmd_line.GetSwitchValuePath(
+            WideToASCII(installer_util::switches::kInstallerData));
         install_status = installer::InstallOrUpdateChrome(
-            cmd_line.program(), archive_to_copy, temp_path.ToWStringHack(),
+            cmd_line.GetProgram(), archive_to_copy, temp_path,
             prefs_source_path, prefs, *installer_version, installed_version);
 
         int install_msg_base = IDS_INSTALL_FAILED_BASE;
         std::wstring chrome_exe;
         if (install_status != installer_util::INSTALL_FAILED) {
-          chrome_exe = installer::GetChromeInstallPath(system_level);
+          chrome_exe = installer::GetChromeInstallPath(system_level).value();
           if (chrome_exe.empty()) {
             // If we failed to construct install path, it means the OS call to
             // get %ProgramFiles% or %AppData% failed. Report this as failure.
@@ -309,12 +297,11 @@ installer_util::InstallStatus InstallChrome(const CommandLine& cmd_line,
   // and master profile file if present.
   scoped_ptr<WorkItemList> cleanup_list(WorkItem::CreateWorkItemList());
   LOG(INFO) << "Deleting temporary directory " << temp_path.value();
-  cleanup_list->AddDeleteTreeWorkItem(temp_path.ToWStringHack(),
-                                      std::wstring());
+  cleanup_list->AddDeleteTreeWorkItem(temp_path, FilePath());
   if (cmd_line.HasSwitch(installer_util::switches::kInstallerData)) {
-    std::wstring prefs_path = cmd_line.GetSwitchValue(
-        installer_util::switches::kInstallerData);
-    cleanup_list->AddDeleteTreeWorkItem(prefs_path, std::wstring());
+    FilePath prefs_path = cmd_line.GetSwitchValuePath(
+        WideToASCII(installer_util::switches::kInstallerData));
+    cleanup_list->AddDeleteTreeWorkItem(prefs_path, FilePath());
   }
   cleanup_list->Do();
 
@@ -340,9 +327,9 @@ installer_util::InstallStatus UninstallChrome(const CommandLine& cmd_line,
   bool remove_all = !cmd_line.HasSwitch(
       installer_util::switches::kDoNotRemoveSharedItems);
 
-  return installer_setup::UninstallChrome(cmd_line.program(), system_install,
-                                          remove_all, force,
-                                          cmd_line, cmd_params);
+  return installer_setup::UninstallChrome(cmd_line.GetProgram(), system_install,
+                                          remove_all, force, cmd_line,
+                                          cmd_params);
 }
 
 installer_util::InstallStatus ShowEULADialog(const std::wstring& inner_frame) {
@@ -394,7 +381,7 @@ bool HandleNonInstallCmdLineOptions(const CommandLine& cmd_line,
           installer_util::switches::kUpdateSetupExe);
       LOG(INFO) << "Opening archive " << setup_patch;
       std::wstring uncompressed_patch;
-      if (LzmaUtil::UnPackArchive(setup_patch, temp_path.ToWStringHack(),
+      if (LzmaUtil::UnPackArchive(setup_patch, temp_path.value(),
                                   &uncompressed_patch) == NO_ERROR) {
         std::wstring old_setup_exe = cmd_line.program();
         std::wstring new_setup_exe = cmd_line.GetSwitchValue(
diff --git a/chrome/installer/setup/uninstall.cc b/chrome/installer/setup/uninstall.cc
index 16c07c1..2ffef62 100644
--- a/chrome/installer/setup/uninstall.cc
+++ b/chrome/installer/setup/uninstall.cc
@@ -70,12 +70,11 @@ bool CurrentUserHasDefaultBrowser(bool system_uninstall) {
   RegKey key(HKEY_LOCAL_MACHINE, reg_key.c_str());
   std::wstring reg_exe;
   if (key.ReadValue(L"", &reg_exe) && reg_exe.length() > 2) {
-    std::wstring chrome_exe = installer::GetChromeInstallPath(system_uninstall);
-    file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
+    FilePath chrome_exe(installer::GetChromeInstallPath(system_uninstall));
+    chrome_exe = chrome_exe.Append(installer_util::kChromeExe);
     reg_exe = reg_exe.substr(1, reg_exe.length() - 2);
-    if ((reg_exe.size() == chrome_exe.size()) &&
-        (std::equal(chrome_exe.begin(), chrome_exe.end(),
-                    reg_exe.begin(), CaseInsensitiveCompare<wchar_t>())))
+    FilePath reg_path(reg_exe);
+    if (chrome_exe == reg_path)
       return true;
   }
 
@@ -169,27 +168,29 @@ enum DeleteResult {
 // Returns DELETE_FAILED if it could not get the path to the install dir.
 // Returns DELETE_REQUIRES_REBOOT if the files were in use and so were
 // scheduled for deletion on next reboot.
-DeleteResult DeleteFilesAndFolders(const std::wstring& exe_path,
-    bool system_uninstall, const installer::Version& installed_version,
-    std::wstring* local_state_path, bool delete_profile) {
-  std::wstring install_path(installer::GetChromeInstallPath(system_uninstall));
+DeleteResult DeleteFilesAndFolders(const FilePath& exe_path,
+                                   bool system_uninstall,
+                                   const installer::Version& installed_version,
+                                   FilePath* local_state_path,
+                                   bool delete_profile) {
+  FilePath install_path(installer::GetChromeInstallPath(system_uninstall));
   if (install_path.empty()) {
     LOG(ERROR) << "Could not get installation destination path.";
     return DELETE_FAILED;  // Nothing else we can do to uninstall, so we return.
   } else {
-    LOG(INFO) << "install destination path: " << install_path;
+    LOG(INFO) << "install destination path: " << install_path.value();
   }
 
   // Move setup.exe to the temp path.
-  std::wstring setup_exe(installer::GetInstallerPathUnderChrome(
+  FilePath setup_exe(installer::GetInstallerPathUnderChrome(
       install_path, installed_version.GetString()));
-  file_util::AppendToPath(&setup_exe, file_util::GetFilenameFromPath(exe_path));
+  setup_exe = setup_exe.Append(exe_path.BaseName());
 
   FilePath temp_file;
   if (!file_util::CreateTemporaryFile(&temp_file)) {
     LOG(ERROR) << "Failed to create temporary file for setup.exe.";
   } else {
-    FilePath setup_exe_path = FilePath::FromWStringHack(setup_exe);
+    FilePath setup_exe_path(setup_exe);
     file_util::Move(setup_exe_path, temp_file);
   }
 
@@ -208,7 +209,7 @@ DeleteResult DeleteFilesAndFolders(const std::wstring& exe_path,
   if (got_local_state) {
     FilePath user_local_file(
         user_local_state.Append(chrome::kLocalStateFilename));
-    FilePath path = FilePath::FromWStringHack(*local_state_path);
+    FilePath path = *local_state_path;
     if (!file_util::CreateTemporaryFile(&path))
       LOG(ERROR) << "Failed to create temporary file for Local State.";
     else
@@ -219,20 +220,21 @@ DeleteResult DeleteFilesAndFolders(const std::wstring& exe_path,
 
   DeleteResult result = DELETE_SUCCEEDED;
 
-  LOG(INFO) << "Deleting install path " << install_path;
+  LOG(INFO) << "Deleting install path " << install_path.value();
   if (!file_util::Delete(install_path, true)) {
-    LOG(ERROR) << "Failed to delete folder (1st try): " << install_path;
+    LOG(ERROR) << "Failed to delete folder (1st try): " << install_path.value();
     if (InstallUtil::IsChromeFrameProcess()) {
       // We don't try killing Chrome processes for Chrome Frame builds since
       // that is unlikely to help. Instead, schedule files for deletion and
       // return a value that will trigger a reboot prompt.
-      ScheduleDirectoryForDeletion(install_path.c_str());
+      ScheduleDirectoryForDeletion(install_path.value().c_str());
       result = DELETE_REQUIRES_REBOOT;
     } else {
       // Try closing any running chrome processes and deleting files once again.
       CloseAllChromeProcesses();
       if (!file_util::Delete(install_path, true)) {
-        LOG(ERROR) << "Failed to delete folder (2nd try): " << install_path;
+        LOG(ERROR) << "Failed to delete folder (2nd try): " <<
+            install_path.value();
         result = DELETE_FAILED;
       }
     }
@@ -265,7 +267,7 @@ DeleteResult DeleteFilesAndFolders(const std::wstring& exe_path,
   } else {
     // Now check and delete if the parent directories are empty
     // For example Google\Chrome or Chromium
-    DeleteEmptyParentDir(install_path);
+    DeleteEmptyParentDir(install_path.value());
   }
   return result;
 }
@@ -425,9 +427,12 @@ const wchar_t kChromeExtProgId[] = L"ChromiumExt";
 }
 
 installer_util::InstallStatus installer_setup::UninstallChrome(
-    const std::wstring& exe_path, bool system_uninstall,
-    bool remove_all, bool force_uninstall,
-    const CommandLine& cmd_line, const wchar_t* cmd_params) {
+    const FilePath& exe_path,
+    bool system_uninstall,
+    bool remove_all,
+    bool force_uninstall,
+    const CommandLine& cmd_line,
+    const wchar_t* cmd_params) {
   installer_util::InstallStatus status = installer_util::UNINSTALL_CONFIRMED;
   std::wstring suffix;
   if (!ShellUtil::GetUserSpecificDefaultBrowserSuffix(&suffix))
@@ -517,12 +522,14 @@ installer_util::InstallStatus installer_setup::UninstallChrome(
 
     if (installed_version.get()) {
       // Unregister any dll servers that we may have registered.
-      std::wstring dll_path(installer::GetChromeInstallPath(system_uninstall));
-      file_util::AppendToPath(&dll_path, installed_version->GetString());
+      FilePath dll_path(installer::GetChromeInstallPath(system_uninstall));
+      dll_path = dll_path.Append(installed_version->GetString());
 
       scoped_ptr<WorkItemList> dll_list(WorkItem::CreateWorkItemList());
-      if (InstallUtil::BuildDLLRegistrationList(dll_path, kDllsToRegister,
-                                                kNumDllsToRegister, false,
+      if (InstallUtil::BuildDLLRegistrationList(dll_path.value(),
+                                                kDllsToRegister,
+                                                kNumDllsToRegister,
+                                                false,
                                                 dll_list.get())) {
         dll_list->Do();
       }
@@ -536,11 +543,11 @@ installer_util::InstallStatus installer_setup::UninstallChrome(
   // and the user's Local State to a temp location.
   bool delete_profile = (status == installer_util::UNINSTALL_DELETE_PROFILE) ||
       (cmd_line.HasSwitch(installer_util::switches::kDeleteProfile));
-  std::wstring local_state_path;
+  FilePath local_state_path;
   ret = installer_util::UNINSTALL_SUCCESSFUL;
 
-  DeleteResult delete_result = DeleteFilesAndFolders(exe_path,
-      system_uninstall, *installed_version, &local_state_path, delete_profile);
+  DeleteResult delete_result = DeleteFilesAndFolders(exe_path, system_uninstall,
+      *installed_version, &local_state_path, delete_profile);
   if (delete_result == DELETE_FAILED) {
     ret = installer_util::UNINSTALL_FAILED;
   } else if (delete_result == DELETE_REQUIRES_REBOOT) {
diff --git a/chrome/installer/setup/uninstall.h b/chrome/installer/setup/uninstall.h
index a2320ad..a0be3d6 100644
--- a/chrome/installer/setup/uninstall.h
+++ b/chrome/installer/setup/uninstall.h
@@ -15,6 +15,8 @@
 #include "chrome/installer/util/util_constants.h"
 #include "chrome/installer/util/version.h"
 
+class FilePath;
+
 namespace installer_setup {
 // This function removes all Chrome registration related keys. It returns true
 // if successful, otherwise false. The error code is set in |exit_code|.
@@ -42,10 +44,12 @@ void RemoveLegacyRegistryKeys();
 // cmd_line: CommandLine that contains information about the command that
 //           was used to launch current uninstaller.
 // cmd_params: Command line parameters passed to the uninstaller.
-installer_util::InstallStatus UninstallChrome(
-    const std::wstring& exe_path, bool system_uninstall,
-    bool remove_all, bool force_uninstall,
-    const CommandLine& cmd_line, const wchar_t* cmd_params);
+installer_util::InstallStatus UninstallChrome(const FilePath& exe_path,
+                                              bool system_uninstall,
+                                              bool remove_all,
+                                              bool force_uninstall,
+                                              const CommandLine& cmd_line,
+                                              const wchar_t* cmd_params);
 
 }  // namespace installer_setup
 
diff --git a/chrome/installer/util/browser_distribution.cc b/chrome/installer/util/browser_distribution.cc
index fe9884f..e5f1af9 100644
--- a/chrome/installer/util/browser_distribution.cc
+++ b/chrome/installer/util/browser_distribution.cc
@@ -40,7 +40,7 @@ BrowserDistribution* BrowserDistribution::GetDistribution(bool chrome_frame) {
 }
 
 void BrowserDistribution::DoPostUninstallOperations(
-    const installer::Version& version, const std::wstring& local_data_path,
+    const installer::Version& version, const FilePath& local_data_path,
     const std::wstring& distribution_data) {
 }
 
diff --git a/chrome/installer/util/browser_distribution.h b/chrome/installer/util/browser_distribution.h
index 8948bdc..2ffb74c 100644
--- a/chrome/installer/util/browser_distribution.h
+++ b/chrome/installer/util/browser_distribution.h
@@ -11,6 +11,7 @@
 #include "chrome/installer/util/util_constants.h"
 #include "chrome/installer/util/version.h"
 
+class FilePath;
 class RegKey;
 
 class BrowserDistribution {
@@ -20,7 +21,7 @@ class BrowserDistribution {
   static BrowserDistribution* GetDistribution();
 
   virtual void DoPostUninstallOperations(const installer::Version& version,
-                                         const std::wstring& local_data_path,
+                                         const FilePath& local_data_path,
                                          const std::wstring& distribution_data);
 
   virtual std::wstring GetAppGuid();
diff --git a/chrome/installer/util/copy_tree_work_item.cc b/chrome/installer/util/copy_tree_work_item.cc
index 22007990..d161ed9 100644
--- a/chrome/installer/util/copy_tree_work_item.cc
+++ b/chrome/installer/util/copy_tree_work_item.cc
@@ -14,11 +14,11 @@ CopyTreeWorkItem::~CopyTreeWorkItem() {
   }
 }
 
-CopyTreeWorkItem::CopyTreeWorkItem(const std::wstring& source_path,
-                                   const std::wstring& dest_path,
-                                   const std::wstring& temp_dir,
+CopyTreeWorkItem::CopyTreeWorkItem(const FilePath& source_path,
+                                   const FilePath& dest_path,
+                                   const FilePath& temp_dir,
                                    CopyOverWriteOption overwrite_option,
-                                   const std::wstring& alternative_path)
+                                   const FilePath& alternative_path)
     : source_path_(source_path),
       dest_path_(dest_path),
       temp_dir_(temp_dir),
diff --git a/chrome/installer/util/copy_tree_work_item.h b/chrome/installer/util/copy_tree_work_item.h
index b899324..c1478922 100644
--- a/chrome/installer/util/copy_tree_work_item.h
+++ b/chrome/installer/util/copy_tree_work_item.h
@@ -35,11 +35,11 @@ class CopyTreeWorkItem : public WorkItem {
   // Notes on temp_path: to facilitate rollback, the caller needs to supply
   // a temporary directory to save the original files if they exist under
   // dest_path.
-  CopyTreeWorkItem(const std::wstring& source_path,
-                   const std::wstring& dest_path,
-                   const std::wstring& temp_dir,
+  CopyTreeWorkItem(const FilePath& source_path,
+                   const FilePath& dest_path,
+                   const FilePath& temp_dir,
                    CopyOverWriteOption overwrite_option,
-                   const std::wstring& alternative_path);
+                   const FilePath& alternative_path);
 
   // Checks if the path specified is in use (and hence can not be deleted)
   bool IsFileInUse(const FilePath& path);
diff --git a/chrome/installer/util/copy_tree_work_item_unittest.cc b/chrome/installer/util/copy_tree_work_item_unittest.cc
index bc187e61..a9aa986 100644
--- a/chrome/installer/util/copy_tree_work_item_unittest.cc
+++ b/chrome/installer/util/copy_tree_work_item_unittest.cc
@@ -108,9 +108,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFile) {
 
   // test Do()
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
+      WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                       file_name_to,
+                                       temp_dir_,
                                        WorkItem::ALWAYS));
 
   EXPECT_TRUE(work_item->Do());
@@ -149,9 +149,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFileOverwrite) {
 
   // test Do() with always_overwrite being true.
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
+      WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                       file_name_to,
+                                       temp_dir_,
                                        WorkItem::ALWAYS));
 
   EXPECT_TRUE(work_item->Do());
@@ -172,9 +172,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFileOverwrite) {
   // test Do() with always_overwrite being false.
   // the file is still overwritten since the content is different.
   work_item.reset(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
+      WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                       file_name_to,
+                                       temp_dir_,
                                        WorkItem::IF_DIFFERENT));
 
   EXPECT_TRUE(work_item->Do());
@@ -221,9 +221,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFileSameContent) {
 
   // test Do() with always_overwrite being true.
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
+      WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                       file_name_to,
+                                       temp_dir_,
                                        WorkItem::ALWAYS));
 
   EXPECT_TRUE(work_item->Do());
@@ -249,9 +249,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFileSameContent) {
 
   // test Do() with always_overwrite being false. nothing should change.
   work_item.reset(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
+      WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                       file_name_to,
+                                       temp_dir_,
                                        WorkItem::IF_DIFFERENT));
 
   EXPECT_TRUE(work_item->Do());
@@ -300,9 +300,9 @@ TEST_F(CopyTreeWorkItemTest, CopyFileAndCleanup) {
   {
     // test Do().
     scoped_ptr<CopyTreeWorkItem> work_item(
-        WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                         file_name_to.ToWStringHack(),
-                                         temp_dir_.ToWStringHack(),
+        WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                         file_name_to,
+                                         temp_dir_,
                                          WorkItem::IF_DIFFERENT));
 
     EXPECT_TRUE(work_item->Do());
@@ -362,10 +362,8 @@ TEST_F(CopyTreeWorkItemTest, CopyFileInUse) {
 
   // test Do().
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
-                                       WorkItem::IF_DIFFERENT));
+      WorkItem::CreateCopyTreeWorkItem(file_name_from, file_name_to, temp_dir_,
+          WorkItem::IF_DIFFERENT));
 
   EXPECT_TRUE(work_item->Do());
 
@@ -440,11 +438,8 @@ TEST_F(CopyTreeWorkItemTest, NewNameAndCopyTest) {
 
   // test Do().
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                       file_name_to.ToWStringHack(),
-                                       temp_dir_.ToWStringHack(),
-                                       WorkItem::NEW_NAME_IF_IN_USE,
-                                       alternate_to.ToWStringHack()));
+      WorkItem::CreateCopyTreeWorkItem(file_name_from, file_name_to, temp_dir_,
+          WorkItem::NEW_NAME_IF_IN_USE, alternate_to));
 
   EXPECT_TRUE(work_item->Do());
 
@@ -474,10 +469,11 @@ TEST_F(CopyTreeWorkItemTest, NewNameAndCopyTest) {
   CloseHandle(pi.hThread);
 
   // Now the process has terminated, lets try overwriting the file again
-  work_item.reset(WorkItem::CreateCopyTreeWorkItem(
-      file_name_from.ToWStringHack(), file_name_to.ToWStringHack(),
-      temp_dir_.ToWStringHack(), WorkItem::NEW_NAME_IF_IN_USE,
-      alternate_to.ToWStringHack()));
+  work_item.reset(WorkItem::CreateCopyTreeWorkItem(file_name_from,
+                                                   file_name_to,
+                                                   temp_dir_,
+                                                   WorkItem::NEW_NAME_IF_IN_USE,
+                                                   alternate_to));
   if (IsFileInUse(file_name_to))
     PlatformThread::Sleep(2000);
   // If file is still in use, the rest of the test will fail.
@@ -536,9 +532,8 @@ TEST_F(CopyTreeWorkItemTest, IfNotPresentTest) {
 
   // test Do().
   scoped_ptr<CopyTreeWorkItem> work_item(
-      WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-          file_name_to.ToWStringHack(), temp_dir_.ToWStringHack(),
-          WorkItem::IF_NOT_PRESENT, L""));
+      WorkItem::CreateCopyTreeWorkItem(file_name_from, file_name_to, temp_dir_,
+          WorkItem::IF_NOT_PRESENT, FilePath()));
   EXPECT_TRUE(work_item->Do());
 
   // verify that the source, destination have not changed and backup path
@@ -562,9 +557,8 @@ TEST_F(CopyTreeWorkItemTest, IfNotPresentTest) {
 
   // Now delete the destination and try copying the file again.
   file_util::Delete(file_name_to, true);
-  work_item.reset(WorkItem::CreateCopyTreeWorkItem(
-      file_name_from.ToWStringHack(), file_name_to.ToWStringHack(),
-      temp_dir_.ToWStringHack(), WorkItem::IF_NOT_PRESENT, L""));
+  work_item.reset(WorkItem::CreateCopyTreeWorkItem(file_name_from, file_name_to,
+      temp_dir_, WorkItem::IF_NOT_PRESENT, FilePath()));
   EXPECT_TRUE(work_item->Do());
 
   // verify that the source, destination are the same and backup path
@@ -627,10 +621,8 @@ TEST_F(CopyTreeWorkItemTest, CopyFileInUseAndCleanup) {
   // test Do().
   {
     scoped_ptr<CopyTreeWorkItem> work_item(
-        WorkItem::CreateCopyTreeWorkItem(file_name_from.ToWStringHack(),
-                                         file_name_to.ToWStringHack(),
-                                         temp_dir_.ToWStringHack(),
-                                         WorkItem::IF_DIFFERENT));
+        WorkItem::CreateCopyTreeWorkItem(file_name_from, file_name_to,
+            temp_dir_, WorkItem::IF_DIFFERENT));
 
     EXPECT_TRUE(work_item->Do());
 
@@ -688,10 +680,8 @@ TEST_F(CopyTreeWorkItemTest, CopyTree) {
   // test Do()
   {
     scoped_ptr<CopyTreeWorkItem> work_item(
-        WorkItem::CreateCopyTreeWorkItem(dir_name_from.ToWStringHack(),
-                                         dir_name_to.ToWStringHack(),
-                                         temp_dir_.ToWStringHack(),
-                                         WorkItem::ALWAYS));
+        WorkItem::CreateCopyTreeWorkItem(dir_name_from, dir_name_to, temp_dir_,
+            WorkItem::ALWAYS));
 
     EXPECT_TRUE(work_item->Do());
   }
diff --git a/chrome/installer/util/delete_tree_work_item.cc b/chrome/installer/util/delete_tree_work_item.cc
index 839f6bb..531f10a 100644
--- a/chrome/installer/util/delete_tree_work_item.cc
+++ b/chrome/installer/util/delete_tree_work_item.cc
@@ -21,8 +21,8 @@ DeleteTreeWorkItem::~DeleteTreeWorkItem() {
   }
 }
 
-DeleteTreeWorkItem::DeleteTreeWorkItem(const std::wstring& root_path,
-                                       const std::wstring& key_path)
+DeleteTreeWorkItem::DeleteTreeWorkItem(const FilePath& root_path,
+                                       const FilePath& key_path)
     : root_path_(root_path),
       key_path_(key_path) {
 }
diff --git a/chrome/installer/util/delete_tree_work_item.h b/chrome/installer/util/delete_tree_work_item.h
index b5bcb50..ff347dd 100644
--- a/chrome/installer/util/delete_tree_work_item.h
+++ b/chrome/installer/util/delete_tree_work_item.h
@@ -30,8 +30,8 @@ class DeleteTreeWorkItem : public WorkItem {
   // Get a backup path that can keep root_path_ or key_path_
   bool GetBackupPath(const FilePath& for_path, FilePath* backup_path);
 
-  DeleteTreeWorkItem(const std::wstring& root_path,
-                     const std::wstring& key_path);
+  DeleteTreeWorkItem(const FilePath& root_path,
+                     const FilePath& key_path);
 
   // Root path to delete.
   FilePath root_path_;
diff --git a/chrome/installer/util/delete_tree_work_item_unittest.cc b/chrome/installer/util/delete_tree_work_item_unittest.cc
index 02c2bb0..acd66cc 100644
--- a/chrome/installer/util/delete_tree_work_item_unittest.cc
+++ b/chrome/installer/util/delete_tree_work_item_unittest.cc
@@ -87,8 +87,7 @@ TEST_F(DeleteTreeWorkItemTest, DeleteTreeNoKeyPath) {
 
   // test Do()
   scoped_ptr<DeleteTreeWorkItem> work_item(
-      WorkItem::CreateDeleteTreeWorkItem(dir_name_delete.ToWStringHack(),
-                                         std::wstring()));
+      WorkItem::CreateDeleteTreeWorkItem(dir_name_delete, FilePath()));
   EXPECT_TRUE(work_item->Do());
 
   // everything should be gone
@@ -135,8 +134,7 @@ TEST_F(DeleteTreeWorkItemTest, DeleteTree) {
 
   // test Do()
   scoped_ptr<DeleteTreeWorkItem> work_item(
-      WorkItem::CreateDeleteTreeWorkItem(dir_name_delete.ToWStringHack(),
-                                         file_name_delete_1.ToWStringHack()));
+      WorkItem::CreateDeleteTreeWorkItem(dir_name_delete, file_name_delete_1));
   EXPECT_TRUE(work_item->Do());
 
   // everything should be gone
@@ -204,8 +202,7 @@ TEST_F(DeleteTreeWorkItemTest, DeleteTreeInUse) {
   // test Do().
   {
     scoped_ptr<DeleteTreeWorkItem> work_item(
-        WorkItem::CreateDeleteTreeWorkItem(dir_name_delete.ToWStringHack(),
-                                           key_path.ToWStringHack()));
+        WorkItem::CreateDeleteTreeWorkItem(dir_name_delete, key_path));
 
     // delete should fail as file in use.
     EXPECT_FALSE(work_item->Do());
diff --git a/chrome/installer/util/google_chrome_distribution.cc b/chrome/installer/util/google_chrome_distribution.cc
index faf574b..b3a09c4 100644
--- a/chrome/installer/util/google_chrome_distribution.cc
+++ b/chrome/installer/util/google_chrome_distribution.cc
@@ -68,11 +68,11 @@ int FileTimeToHours(const FILETIME& time) {
 
 // Returns the directory last write time in hours since January 1, 1601.
 // Returns -1 if there was an error retrieving the directory time.
-int GetDirectoryWriteTimeInHours(const wchar_t* path) {
+int GetDirectoryWriteTimeInHours(const FilePath& path) {
   // To open a directory you need to pass FILE_FLAG_BACKUP_SEMANTICS.
   DWORD share = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
-  HANDLE file = ::CreateFileW(path, 0, share, NULL, OPEN_EXISTING,
-                              FILE_FLAG_BACKUP_SEMANTICS, NULL);
+  HANDLE file = ::CreateFileW(path.value().c_str(), 0, share, NULL,
+                              OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
   if (INVALID_HANDLE_VALUE == file)
     return -1;
   FILETIME time;
@@ -84,7 +84,7 @@ int GetDirectoryWriteTimeInHours(const wchar_t* path) {
 // Returns the directory last-write time age in hours, relative to current
 // time, so if it returns 14 it means that the directory was last written 14
 // hours ago. Returns -1 if there was an error retrieving the directory.
-int GetDirectoryWriteAgeInHours(const wchar_t* path) {
+int GetDirectoryWriteAgeInHours(const FilePath& path) {
   int dir_time = GetDirectoryWriteTimeInHours(path);
   if (dir_time < 0)
     return dir_time;
@@ -128,9 +128,9 @@ bool GoogleChromeDistribution::BuildUninstallMetricsString(
 }
 
 bool GoogleChromeDistribution::ExtractUninstallMetricsFromFile(
-    const std::wstring& file_path, std::wstring* uninstall_metrics_string) {
+    const FilePath& file_path, std::wstring* uninstall_metrics_string) {
 
-  JSONFileValueSerializer json_serializer(FilePath::FromWStringHack(file_path));
+  JSONFileValueSerializer json_serializer(file_path);
 
   std::string json_error_string;
   scoped_ptr<Value> root(json_serializer.Deserialize(NULL));
@@ -172,7 +172,7 @@ bool GoogleChromeDistribution::ExtractUninstallMetrics(
 }
 
 void GoogleChromeDistribution::DoPostUninstallOperations(
-    const installer::Version& version, const std::wstring& local_data_path,
+    const installer::Version& version, const FilePath& local_data_path,
     const std::wstring& distribution_data) {
   // Send the Chrome version and OS version as params to the form.
   // It would be nice to send the locale, too, but I don't see an
@@ -447,9 +447,9 @@ void GoogleChromeDistribution::LaunchUserExperiment(
     LOG(INFO) << "User in experiment locale";
     // Check browser usage inactivity by the age of the last-write time of the
     // chrome user data directory. Ninety days is our trigger.
-    std::wstring user_data_dir = installer::GetChromeUserDataPath();
+    FilePath user_data_dir(installer::GetChromeUserDataPath());
     const int kSixtyDays = 60 * 24;
-    int dir_age_hours = GetDirectoryWriteAgeInHours(user_data_dir.c_str());
+    int dir_age_hours = GetDirectoryWriteAgeInHours(user_data_dir);
     if (dir_age_hours < kSixtyDays)
       return;
     // At this point the user qualifies for the experiment, however we need to
diff --git a/chrome/installer/util/google_chrome_distribution.h b/chrome/installer/util/google_chrome_distribution.h
index c696e61..2e88858 100644
--- a/chrome/installer/util/google_chrome_distribution.h
+++ b/chrome/installer/util/google_chrome_distribution.h
@@ -14,6 +14,7 @@
 #include "testing/gtest/include/gtest/gtest_prod.h"  // for FRIEND_TEST
 
 class DictionaryValue;
+class FilePath;
 
 class GoogleChromeDistribution : public BrowserDistribution {
  public:
@@ -27,7 +28,7 @@ class GoogleChromeDistribution : public BrowserDistribution {
   //   concatenated to the survey url if the file in local_data_path indicates
   //   the user has opted in to providing anonymous usage data.
   virtual void DoPostUninstallOperations(const installer::Version& version,
-                                         const std::wstring& local_data_path,
+                                         const FilePath& local_data_path,
                                          const std::wstring& distribution_data);
 
   virtual std::wstring GetAppGuid();
@@ -51,7 +52,8 @@ class GoogleChromeDistribution : public BrowserDistribution {
   // install_status: if 0, means installation was successful.
   // value: current value of Google Update "ap" key.
   std::wstring GetNewGoogleUpdateApKey(bool diff_install,
-      installer_util::InstallStatus status, const std::wstring& value);
+                                       installer_util::InstallStatus status,
+                                       const std::wstring& value);
 
   virtual std::wstring GetPublisherName();
 
@@ -100,12 +102,12 @@ class GoogleChromeDistribution : public BrowserDistribution {
   // has GET parameters, i.e. &metric1=foo&metric2=bar.
   // Returns true if uninstall_metrics has been successfully populated with
   // the uninstall metrics, false otherwise.
-  virtual bool ExtractUninstallMetricsFromFile(
-      const std::wstring& file_path, std::wstring* uninstall_metrics);
+  virtual bool ExtractUninstallMetricsFromFile(const FilePath& file_path,
+                                               std::wstring* uninstall_metrics);
 
   // Extracts uninstall metrics from the given JSON value.
   virtual bool ExtractUninstallMetrics(const DictionaryValue& root,
-      std::wstring* uninstall_metrics);
+                                       std::wstring* uninstall_metrics);
 
   // Given a DictionaryValue containing a set of uninstall metrics,
   // this builds a URL parameter list of all the contained metrics.
diff --git a/chrome/installer/util/helper.cc b/chrome/installer/util/helper.cc
index af18e9e..a2038c4 100644
--- a/chrome/installer/util/helper.cc
+++ b/chrome/installer/util/helper.cc
@@ -18,8 +18,8 @@
 
 namespace {
 
-std::wstring GetChromeInstallBasePath(bool system_install,
-                                      const wchar_t* subpath) {
+FilePath GetChromeInstallBasePath(bool system_install,
+                                  const wchar_t* subpath) {
   FilePath install_path;
   if (system_install) {
     PathService::Get(base::DIR_PROGRAM_FILES, &install_path);
@@ -31,41 +31,42 @@ std::wstring GetChromeInstallBasePath(bool system_install,
     install_path = install_path.Append(dist->GetInstallSubDir());
     install_path = install_path.Append(subpath);
   }
-  return install_path.ToWStringHack();
+  return install_path;
 }
 
 }  // namespace
 
-std::wstring installer::GetChromeInstallPath(bool system_install) {
+FilePath installer::GetChromeInstallPath(bool system_install) {
   return GetChromeInstallBasePath(system_install,
                                   installer_util::kInstallBinaryDir);
 }
 
-std::wstring installer::GetChromeUserDataPath() {
+FilePath installer::GetChromeUserDataPath() {
   return GetChromeInstallBasePath(false, installer_util::kInstallUserDataDir);
 }
 
 bool installer::LaunchChrome(bool system_install) {
-  std::wstring chrome_exe(L"\"");
-  chrome_exe.append(installer::GetChromeInstallPath(system_install));
-  file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
-  chrome_exe.append(L"\"");
-  return base::LaunchApp(chrome_exe, false, false, NULL);
+  FilePath chrome_exe(FILE_PATH_LITERAL("\""));
+  chrome_exe = chrome_exe.Append(installer::GetChromeInstallPath(
+      system_install));
+  chrome_exe = chrome_exe.Append(installer_util::kChromeExe);
+  chrome_exe = chrome_exe.Append(FILE_PATH_LITERAL("\""));
+  return base::LaunchApp(chrome_exe.value(), false, false, NULL);
 }
 
 bool installer::LaunchChromeAndWaitForResult(bool system_install,
                                              const std::wstring& options,
                                              int32* exit_code) {
-  std::wstring chrome_exe(installer::GetChromeInstallPath(system_install));
+  FilePath chrome_exe(installer::GetChromeInstallPath(system_install));
   if (chrome_exe.empty())
     return false;
-  file_util::AppendToPath(&chrome_exe, installer_util::kChromeExe);
+  chrome_exe = chrome_exe.Append(installer_util::kChromeExe);
 
-  std::wstring command_line(L"\"" + chrome_exe + L"\"");
+  std::wstring command_line(L"\"" + chrome_exe.value() + L"\"");
   command_line.append(options);
   STARTUPINFOW si = {sizeof(si)};
   PROCESS_INFORMATION pi = {0};
-  if (!::CreateProcessW(chrome_exe.c_str(),
+  if (!::CreateProcessW(chrome_exe.value().c_str(),
                         const_cast<wchar_t*>(command_line.c_str()),
                         NULL, NULL, FALSE, CREATE_NO_WINDOW, NULL, NULL,
                         &si, &pi)) {
@@ -85,13 +86,13 @@ bool installer::LaunchChromeAndWaitForResult(bool system_install,
   return true;
 }
 
-void installer::RemoveOldVersionDirs(const std::wstring& chrome_path,
+void installer::RemoveOldVersionDirs(const FilePath& chrome_path,
                                      const std::wstring& latest_version_str) {
-  std::wstring search_path(chrome_path);
-  file_util::AppendToPath(&search_path, L"*");
+  FilePath search_path(chrome_path.AppendASCII("*"));
 
   WIN32_FIND_DATA find_file_data;
-  HANDLE file_handle = FindFirstFile(search_path.c_str(), &find_file_data);
+  HANDLE file_handle = FindFirstFile(search_path.value().c_str(),
+                                     &find_file_data);
   if (file_handle == INVALID_HANDLE_VALUE)
     return;
 
@@ -108,11 +109,9 @@ void installer::RemoveOldVersionDirs(const std::wstring& chrome_path,
       version.reset(
           installer::Version::GetVersionFromString(find_file_data.cFileName));
       if (version.get() && latest_version->IsHigherThan(version.get())) {
-        std::wstring remove_dir(chrome_path);
-        file_util::AppendToPath(&remove_dir, find_file_data.cFileName);
-        std::wstring chrome_dll_path(remove_dir);
-        file_util::AppendToPath(&chrome_dll_path, installer_util::kChromeDll);
-        LOG(INFO) << "deleting directory " << remove_dir;
+        FilePath remove_dir(chrome_path.Append(find_file_data.cFileName));
+        FilePath chrome_dll_path(remove_dir.Append(installer_util::kChromeDll));
+        LOG(INFO) << "deleting directory " << remove_dir.value();
         scoped_ptr<DeleteTreeWorkItem> item;
         item.reset(WorkItem::CreateDeleteTreeWorkItem(remove_dir,
                                                       chrome_dll_path));
diff --git a/chrome/installer/util/helper.h b/chrome/installer/util/helper.h
index 132d718..975ec8a 100644
--- a/chrome/installer/util/helper.h
+++ b/chrome/installer/util/helper.h
@@ -9,6 +9,8 @@
 
 #include <string>
 
+class FilePath;
+
 namespace installer {
 
 // This function returns the install path for Chrome depending on whether its
@@ -16,13 +18,13 @@ namespace installer {
 // system_install: if true, the function returns system wide location
 //                 (ProgramFiles\Google). Otherwise it returns user specific
 //                 location (Document And Settings\<user>\Local Settings...)
-std::wstring GetChromeInstallPath(bool system_install);
+FilePath GetChromeInstallPath(bool system_install);
 
 // This function returns the path to the directory that holds the user data,
 // this is always inside "Document And Settings\<user>\Local Settings.". Note
 // that this is the default user data directory and does not take into account
 // that it can be overriden with a command line parameter.
-std::wstring GetChromeUserDataPath();
+FilePath GetChromeUserDataPath();
 
 // Launches Chrome without waiting for its exit.
 bool LaunchChrome(bool system_install);
@@ -42,7 +44,7 @@ bool LaunchChromeAndWaitForResult(bool system_install,
 //
 // chrome_path: the root path of Chrome installation.
 // latest_version_str: the latest version of Chrome installed.
-void RemoveOldVersionDirs(const std::wstring& chrome_path,
+void RemoveOldVersionDirs(const FilePath& chrome_path,
                           const std::wstring& latest_version_str);
 
 }  // namespace installer
diff --git a/chrome/installer/util/helper_unittest.cc b/chrome/installer/util/helper_unittest.cc
index 6ccbd29..fa297a5 100644
--- a/chrome/installer/util/helper_unittest.cc
+++ b/chrome/installer/util/helper_unittest.cc
@@ -105,7 +105,7 @@ TEST_F(SetupHelperTest, Delete) {
   ASSERT_TRUE(file_util::PathExists(chrome_dll_4));
 
   std::wstring latest_version(L"1.0.4.0");
-  installer::RemoveOldVersionDirs(chrome_dir.value(), latest_version);
+  installer::RemoveOldVersionDirs(chrome_dir, latest_version);
 
   // old versions should be gone
   EXPECT_FALSE(file_util::PathExists(chrome_dir_1));
@@ -178,7 +178,7 @@ TEST_F(SetupHelperTest, DeleteInUsed) {
   ASSERT_TRUE(file_util::PathExists(chrome_dll_4));
 
   std::wstring latest_version(L"1.0.4.0");
-  installer::RemoveOldVersionDirs(chrome_dir.value(), latest_version);
+  installer::RemoveOldVersionDirs(chrome_dir, latest_version);
 
   // old versions not in used should be gone
   EXPECT_FALSE(file_util::PathExists(chrome_dir_1));
diff --git a/chrome/installer/util/logging_installer.cc b/chrome/installer/util/logging_installer.cc
index e03c25b..a7ac607 100644
--- a/chrome/installer/util/logging_installer.cc
+++ b/chrome/installer/util/logging_installer.cc
@@ -50,8 +50,7 @@ void EndInstallerLogging() {
 }
 
 std::wstring GetLogFilePath(const CommandLine& command_line) {
-  if (command_line.HasSwitch(
-          WideToASCII(installer_util::switches::kLogFile))) {
+  if (command_line.HasSwitch(WideToASCII(installer_util::switches::kLogFile))) {
     return command_line.GetSwitchValue(
         WideToASCII(installer_util::switches::kLogFile));
   }
@@ -64,10 +63,9 @@ std::wstring GetLogFilePath(const CommandLine& command_line) {
   }
 
   FilePath log_path;
-
   if (PathService::Get(base::DIR_TEMP, &log_path)) {
     log_path = log_path.Append(log_filename);
-    return log_path.ToWStringHack();
+    return log_path.value();
   } else {
     return log_filename;
   }
diff --git a/chrome/installer/util/move_tree_work_item.cc b/chrome/installer/util/move_tree_work_item.cc
index 45c03b2..be5b7af 100644
--- a/chrome/installer/util/move_tree_work_item.cc
+++ b/chrome/installer/util/move_tree_work_item.cc
@@ -14,9 +14,9 @@ MoveTreeWorkItem::~MoveTreeWorkItem() {
   }
 }
 
-MoveTreeWorkItem::MoveTreeWorkItem(const std::wstring& source_path,
-                                   const std::wstring& dest_path,
-                                   const std::wstring& temp_dir)
+MoveTreeWorkItem::MoveTreeWorkItem(const FilePath& source_path,
+                                   const FilePath& dest_path,
+                                   const FilePath& temp_dir)
     : source_path_(source_path),
       dest_path_(dest_path),
       temp_dir_(temp_dir),
diff --git a/chrome/installer/util/move_tree_work_item.h b/chrome/installer/util/move_tree_work_item.h
index cfa86c4..1ab3644 100644
--- a/chrome/installer/util/move_tree_work_item.h
+++ b/chrome/installer/util/move_tree_work_item.h
@@ -33,9 +33,9 @@ class MoveTreeWorkItem : public WorkItem {
   // specified by dest_path. To facilitate rollback, the caller needs to supply
   // a temporary directory (temp_dir) to save the original files if they exist
   // under dest_path.
-  MoveTreeWorkItem(const std::wstring& source_path,
-                   const std::wstring& dest_path,
-                   const std::wstring& temp_dir);
+  MoveTreeWorkItem(const FilePath& source_path,
+                   const FilePath& dest_path,
+                   const FilePath& temp_dir);
 
   // Source path to move files from.
   FilePath source_path_;
diff --git a/chrome/installer/util/move_tree_work_item_unittest.cc b/chrome/installer/util/move_tree_work_item_unittest.cc
index 9662b18..90e6c2b 100644
--- a/chrome/installer/util/move_tree_work_item_unittest.cc
+++ b/chrome/installer/util/move_tree_work_item_unittest.cc
@@ -27,11 +27,11 @@ namespace {
 
       // Create a fresh, empty copy of this test directory.
       file_util::Delete(test_dir_, true);
-      file_util::CreateDirectoryW(test_dir_);
+      file_util::CreateDirectory(test_dir_);
 
       // Create a tempory directory under the test directory.
       temp_dir_ = test_dir_.AppendASCII("temp");
-      file_util::CreateDirectoryW(temp_dir_);
+      file_util::CreateDirectory(temp_dir_);
 
       ASSERT_TRUE(file_util::PathExists(test_dir_));
       ASSERT_TRUE(file_util::PathExists(temp_dir_));
@@ -104,8 +104,7 @@ TEST_F(MoveTreeWorkItemTest, MoveDirectory) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_dir1.ToWStringHack(), to_dir.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_dir1, to_dir, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_FALSE(file_util::PathExists(from_dir1));
@@ -157,8 +156,7 @@ TEST_F(MoveTreeWorkItemTest, MoveDirectoryDestExists) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_dir1.ToWStringHack(), to_dir.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_dir1, to_dir, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_FALSE(file_util::PathExists(from_dir1));
@@ -199,8 +197,7 @@ TEST_F(MoveTreeWorkItemTest, MoveAFile) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_file.ToWStringHack(), to_file.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_file, to_file, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_TRUE(file_util::PathExists(from_dir));
@@ -244,8 +241,7 @@ TEST_F(MoveTreeWorkItemTest, MoveFileDestExists) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_file.ToWStringHack(), to_dir.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_file, to_dir, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_TRUE(file_util::PathExists(from_dir));
@@ -302,8 +298,7 @@ TEST_F(MoveTreeWorkItemTest, MoveFileDestInUse) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_file.ToWStringHack(), to_file.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_file, to_file, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_TRUE(file_util::PathExists(from_dir));
@@ -363,8 +358,7 @@ TEST_F(MoveTreeWorkItemTest, MoveFileInUse) {
 
   // test Do()
   scoped_ptr<MoveTreeWorkItem> work_item(WorkItem::CreateMoveTreeWorkItem(
-      from_file.ToWStringHack(), to_file.ToWStringHack(),
-          temp_dir_.ToWStringHack()));
+      from_file, to_file, temp_dir_));
   EXPECT_TRUE(work_item->Do());
 
   EXPECT_TRUE(file_util::PathExists(from_dir));
diff --git a/chrome/installer/util/work_item.cc b/chrome/installer/util/work_item.cc
index af14379..1c337e1 100644
--- a/chrome/installer/util/work_item.cc
+++ b/chrome/installer/util/work_item.cc
@@ -21,11 +21,11 @@ WorkItem::~WorkItem() {
 }
 
 CopyTreeWorkItem* WorkItem::CreateCopyTreeWorkItem(
-    const std::wstring& source_path,
-    const std::wstring& dest_path,
-    const std::wstring& temp_dir,
+    const FilePath& source_path,
+    const FilePath& dest_path,
+    const FilePath& temp_dir,
     CopyOverWriteOption overwrite_option,
-    const std::wstring& alternative_path) {
+    const FilePath& alternative_path) {
   return new CopyTreeWorkItem(source_path, dest_path, temp_dir,
                               overwrite_option, alternative_path);
 }
@@ -49,14 +49,14 @@ DeleteRegValueWorkItem* WorkItem::CreateDeleteRegValueWorkItem(
 }
 
 DeleteTreeWorkItem* WorkItem::CreateDeleteTreeWorkItem(
-    const std::wstring& root_path, const std::wstring& key_path) {
+    const FilePath& root_path, const FilePath& key_path) {
   return new DeleteTreeWorkItem(root_path, key_path);
 }
 
 MoveTreeWorkItem* WorkItem::CreateMoveTreeWorkItem(
-    const std::wstring& source_path,
-    const std::wstring& dest_path,
-    const std::wstring& temp_dir) {
+    const FilePath& source_path,
+    const FilePath& dest_path,
+    const FilePath& temp_dir) {
   return new MoveTreeWorkItem(source_path, dest_path, temp_dir);
 }
 
diff --git a/chrome/installer/util/work_item.h b/chrome/installer/util/work_item.h
index 9a61363..45b72ae 100644
--- a/chrome/installer/util/work_item.h
+++ b/chrome/installer/util/work_item.h
@@ -46,11 +46,11 @@ class WorkItem {
   // * If overwrite_option is NEW_NAME_IF_IN_USE, file is copied with an
   //   alternate name specified by alternative_path.
   static CopyTreeWorkItem* CreateCopyTreeWorkItem(
-      const std::wstring& source_path,
-      const std::wstring& dest_path,
-      const std::wstring& temp_dir,
+      const FilePath& source_path,
+      const FilePath& dest_path,
+      const FilePath& temp_dir,
       CopyOverWriteOption overwrite_option,
-      const std::wstring& alternative_path = L"");
+      const FilePath& alternative_path = FilePath());
 
   // Create a CreateDirWorkItem that creates a directory at the given path.
   static CreateDirWorkItem* CreateCreateDirWorkItem(const FilePath& path);
@@ -71,14 +71,14 @@ class WorkItem {
   // hierarchy at the given root path. A key file can be optionally specified
   // by key_path.
   static DeleteTreeWorkItem* CreateDeleteTreeWorkItem(
-      const std::wstring& root_path, const std::wstring& key_path);
+      const FilePath& root_path, const FilePath& key_path);
 
   // Create a MoveTreeWorkItem that recursively moves a file system hierarchy
   // from source path to destination path.
   static MoveTreeWorkItem* CreateMoveTreeWorkItem(
-      const std::wstring& source_path,
-      const std::wstring& dest_path,
-      const std::wstring& temp_dir);
+      const FilePath& source_path,
+      const FilePath& dest_path,
+      const FilePath& temp_dir);
 
   // Create a SetRegValueWorkItem that sets a registry value with REG_SZ type
   // at the key with specified path.
diff --git a/chrome/installer/util/work_item_list.cc b/chrome/installer/util/work_item_list.cc
index 8f4c702..76d0dfa 100644
--- a/chrome/installer/util/work_item_list.cc
+++ b/chrome/installer/util/work_item_list.cc
@@ -63,11 +63,11 @@ bool WorkItemList::AddWorkItem(WorkItem* work_item) {
   return true;
 }
 
-bool WorkItemList::AddCopyTreeWorkItem(const std::wstring& source_path,
-                                       const std::wstring& dest_path,
-                                       const std::wstring& temp_dir,
+bool WorkItemList::AddCopyTreeWorkItem(const FilePath& source_path,
+                                       const FilePath& dest_path,
+                                       const FilePath& temp_dir,
                                        CopyOverWriteOption overwrite_option,
-                                       const std::wstring& alternative_path) {
+                                       const FilePath& alternative_path) {
   WorkItem* item = reinterpret_cast<WorkItem*>(
       WorkItem::CreateCopyTreeWorkItem(source_path, dest_path, temp_dir,
                                        overwrite_option, alternative_path));
@@ -97,16 +97,16 @@ bool WorkItemList::AddDeleteRegValueWorkItem(HKEY predefined_root,
   return AddWorkItem(item);
 }
 
-bool WorkItemList::AddDeleteTreeWorkItem(const std::wstring& root_path,
-                                         const std::wstring& key_path) {
+bool WorkItemList::AddDeleteTreeWorkItem(const FilePath& root_path,
+                                         const FilePath& key_path) {
   WorkItem* item = reinterpret_cast<WorkItem*>(
       WorkItem::CreateDeleteTreeWorkItem(root_path, key_path));
   return AddWorkItem(item);
 }
 
-bool WorkItemList::AddMoveTreeWorkItem(const std::wstring& source_path,
-                                       const std::wstring& dest_path,
-                                       const std::wstring& temp_dir) {
+bool WorkItemList::AddMoveTreeWorkItem(const FilePath& source_path,
+                                       const FilePath& dest_path,
+                                       const FilePath& temp_dir) {
   WorkItem* item = reinterpret_cast<WorkItem*>(
       WorkItem::CreateMoveTreeWorkItem(source_path, dest_path, temp_dir));
   return AddWorkItem(item);
diff --git a/chrome/installer/util/work_item_list.h b/chrome/installer/util/work_item_list.h
index 1390701..71bec61 100644
--- a/chrome/installer/util/work_item_list.h
+++ b/chrome/installer/util/work_item_list.h
@@ -36,11 +36,11 @@ class WorkItemList : public WorkItem {
   bool AddWorkItem(WorkItem* work_item);
 
   // Add a CopyTreeWorkItem to the list of work items.
-  bool AddCopyTreeWorkItem(const std::wstring& source_path,
-                           const std::wstring& dest_path,
-                           const std::wstring& temp_dir,
+  bool AddCopyTreeWorkItem(const FilePath& source_path,
+                           const FilePath& dest_path,
+                           const FilePath& temp_dir,
                            CopyOverWriteOption overwrite_option,
-                           const std::wstring& alternative_path = L"");
+                           const FilePath& alternative_path = FilePath());
 
   // Add a CreateDirWorkItem that creates a directory at the given path.
   bool AddCreateDirWorkItem(const FilePath& path);
@@ -59,13 +59,13 @@ class WorkItemList : public WorkItem {
   // Add a DeleteTreeWorkItem that recursively deletes a file system
   // hierarchy at the given root path. A key file can be optionally specified
   // by key_path.
-  bool AddDeleteTreeWorkItem(const std::wstring& root_path,
-                             const std::wstring& key_path);
+  bool AddDeleteTreeWorkItem(const FilePath& root_path,
+                             const FilePath& key_path);
 
   // Add a MoveTreeWorkItem to the list of work items.
-  bool AddMoveTreeWorkItem(const std::wstring& source_path,
-                           const std::wstring& dest_path,
-                           const std::wstring& temp_dir);
+  bool AddMoveTreeWorkItem(const FilePath& source_path,
+                           const FilePath& dest_path,
+                           const FilePath& temp_dir);
 
   // Add a SetRegValueWorkItem that sets a registry value with REG_SZ type
   // at the key with specified path.