Reset user data directory and disk cache directory after downgrade.

chrome/installer/setup/install.cc

 // Copyright (c) 2012 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 "chrome/installer/setup/install.h"
 
 #include <windows.h>
 #include <shlobj.h>
 #include <time.h>
 
 #include <memory>
 #include <string>
 
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/win/registry.h"
 #include "base/win/shortcut.h"
 #include "base/win/windows_version.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/installer/setup/install_worker.h"
 #include "chrome/installer/setup/installer_crash_reporting.h"
 #include "chrome/installer/setup/setup_constants.h"
 #include "chrome/installer/setup/setup_util.h"
 #include "chrome/installer/setup/update_active_setup_version_work_item.h"
 #include "chrome/installer/util/beacons.h"
@@ skipping 248 matching lines @@
   std::vector<base::FilePath::StringType> components;
   file_path.GetComponents(&components);
   if (components.size() <= num_components)
     return file_path;
   base::FilePath truncated_file_path;
   for (size_t i = 0; i < num_components; ++i)
     truncated_file_path = truncated_file_path.Append(components[i]);
   return truncated_file_path;
 }
 
+base::string16 GetDowngradeVersionPath() {
+  return base::string16(L"Software\\Google\\Update\\ClientState\\") +

[grt (UTC plus 2), 2016/05/19 03:24:18]

use BrowserDistribution::GetStateKey() for this rather than computing it

[zmin, 2016/05/19 23:08:03]

Done. Also changed in user_profiles_cleanup.cc

+         base::string16(google_update::kChromeUpgradeCode);
+}
+
+void AddDowngradeVersion(HKEY root, const base::Version* existing_version) {

[grt (UTC plus 2), 2016/05/19 03:24:18]

is it possible to do this work somewhere in AddInstallWorkItems via WorkItems
(maybe Conditional work items) so that rollback will bring them back to their
previous values in case of error?

+  DCHECK(existing_version);
+  base::win::RegKey key(root, GetDowngradeVersionPath().c_str(),
+                        KEY_QUERY_VALUE | KEY_SET_VALUE);
+  if (!key.HasValue(google_update::kRegDowngradeVersion))
+    key.WriteValue(google_update::kRegDowngradeVersion,
+                   base::ASCIIToUTF16(existing_version->GetString()).c_str());
+}
+
+void RemoveDowngradeVersion(HKEY root, const base::Version& new_version) {
+  base::win::RegKey key(root, GetDowngradeVersionPath().c_str(),
+                        KEY_QUERY_VALUE | KEY_SET_VALUE);
+  base::string16 downgrade_version;
+  if (key.ReadValue(google_update::kRegDowngradeVersion, &downgrade_version) ==
+          ERROR_SUCCESS &&
+      base::Version(base::UTF16ToASCII(downgrade_version)) <= new_version)
+    key.DeleteValue(google_update::kRegDowngradeVersion);
+}

[grt (UTC plus 2), 2016/05/19 03:24:18]

nit: blank line after this

[zmin, 2016/05/19 23:08:03]

Done.

 }  // namespace
 
 namespace installer {
 
 void UpdatePerUserShortcutsInLocation(
     const ShellUtil::ShortcutLocation shortcut_location,
     BrowserDistribution* dist,
     const base::FilePath& old_target_dir,
     const base::FilePath& old_target_name_suffix,
     const base::FilePath& new_target_path) {
@@ skipping 358 matching lines @@
       // Chrome to become their default browser on the download page, we must
       // force it here because the master_preferences file will not get copied
       // into the build.
       bool force_chrome_default_for_user = false;
       if (result == NEW_VERSION_UPDATED || result == INSTALL_REPAIRED ||
           result == OLD_VERSION_DOWNGRADE || result == IN_USE_DOWNGRADE) {
         prefs.GetBool(master_preferences::kMakeChromeDefaultForUser,
                       &force_chrome_default_for_user);
       }
 
+      if (result == OLD_VERSION_DOWNGRADE || result == IN_USE_DOWNGRADE)
+        AddDowngradeVersion(installer_state.root_key(), existing_version.get());
+      else if (result == NEW_VERSION_UPDATED || result == IN_USE_UPDATED)
+        RemoveDowngradeVersion(installer_state.root_key(), new_version);
+
       RegisterChromeOnMachine(installer_state, *chrome_product,
           make_chrome_default || force_chrome_default_for_user);
 
       if (!installer_state.system_install()) {
         DCHECK_EQ(chrome_product->distribution(),
                   BrowserDistribution::GetDistribution());
         UpdateDefaultBrowserBeaconForPath(
             installer_state.target_path().Append(installer::kChromeExe));
       }
     }
@@ skipping 97 matching lines @@
   // Read master_preferences copied beside chrome.exe at install.
   MasterPreferences prefs(installation_root.AppendASCII(kDefaultMasterPrefs));
   base::FilePath chrome_exe(installation_root.Append(kChromeExe));
   CreateOrUpdateShortcuts(
       chrome_exe, chrome, prefs, CURRENT_USER, install_operation);
 
   UpdateDefaultBrowserBeaconForPath(chrome_exe);
 }
 
 }  // namespace installer