Reset user data directory and disk cache directory after downgrade.

chrome/installer/util/install_util.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.
 //
 // See the corresponding header file for description of the functions in this
 // file.
 
 #include "chrome/installer/util/install_util.h"
 
 #include <shellapi.h>
@@ skipping 26 matching lines @@
 #include "chrome/installer/util/installation_state.h"
 #include "chrome/installer/util/l10n_string_util.h"
 #include "chrome/installer/util/util_constants.h"
 #include "chrome/installer/util/work_item_list.h"
 
 using base::win::RegKey;
 using installer::ProductState;
 
 namespace {
 
+const wchar_t kRegDowngradeVersion[] = L"DowngrdeVersion";
 const wchar_t kStageBinaryPatching[] = L"binary_patching";
 const wchar_t kStageBuilding[] = L"building";
 const wchar_t kStageConfiguringAutoLaunch[] = L"configuring_auto_launch";
 const wchar_t kStageCopyingPreferencesFile[] = L"copying_prefs";
 const wchar_t kStageCreatingShortcuts[] = L"creating_shortcuts";
 const wchar_t kStageEnsemblePatching[] = L"ensemble_patching";
 const wchar_t kStageExecuting[] = L"executing";
 const wchar_t kStageFinishing[] = L"finishing";
 const wchar_t kStagePreconditions[] = L"preconditions";
 const wchar_t kStageRefreshingPolicy[] = L"refreshing_policy";
@@ skipping 563 matching lines @@
 }
 
 // Populate |info| for |file|, returning true on success.
 // static
 bool InstallUtil::ProgramCompare::GetInfo(const base::File& file,
                                           BY_HANDLE_FILE_INFORMATION* info) {
   DCHECK(file.IsValid());
   return GetFileInformationByHandle(file.GetPlatformFile(), info) != 0;
 }
 
+// static
+base::Version InstallUtil::GetDowngradeVersion(HKEY root) {

[grt (UTC plus 2), 2016/05/19 23:39:28]

i think it's cleaner for this to take a bool system_install rather than the
HKEY. it should also take the const AppRegistrationData& as mentioned below

[zmin, 2016/05/20 00:52:25]

I use HKEY instead of bool here because
1) Make it same as the functions below. The AddDowngradeVersionItem function is
called in install_worker.cc which the root key is get directly from
installer_state.root_key().
2) This function is also called by AddDowngradeVersionItem(), using HKEY avoid
converting between bool and HKEY

[grt (UTC plus 2), 2016/05/20 15:25:05]

using HKEY leaks an implementation detail into the interface. why should
MoveUserDataForFirstRunAfterDowngrade need to know that the value is stored in
the registry, and know how to figure out which hive to look in? i think it's
fine if this takes a bool and the fn below takes an HKEY. also fine to to the
bool->HKEY here and down below. could also have the fn below take a const
InstallerState& and use its root_key() method, but that may make unittesting
more difficult.

[zmin, 2016/05/20 16:33:05]

Sure, I'll do bool for both.

+  base::win::RegKey key;
+  base::string16 downgrade_version;
+  if (key.Open(root,
+               BrowserDistribution::GetDistribution()->GetStateKey().c_str(),
+               KEY_QUERY_VALUE | KEY_WOW64_32KEY) != ERROR_SUCCESS ||
+      key.ReadValue(kRegDowngradeVersion, &downgrade_version) !=
+          ERROR_SUCCESS) {
+    return base::Version();
+  }
+  return base::Version(base::UTF16ToASCII(downgrade_version));
+}
+
+// static
+void InstallUtil::AddSetDowngradeVersionItem(

[grt (UTC plus 2), 2016/05/19 23:39:28]

this should take a const AppRegistrationData& as input rather than call
BrowserDistribution::GetDistribution(). same for below.

[zmin, 2016/05/20 00:52:25]

Done. But I'll use BrowserDistribution* which is a wrapper of
AppRegistrationData.

[grt (UTC plus 2), 2016/05/20 15:25:05]

Why? I think it'll be easier to unittest using ARD.

[zmin, 2016/05/20 16:33:05]

There is no much difference. BrowserDistribution->GetStateKey just simply call
ARD->GetStateKey. Unittest works fine with BrowserDistribution.

+    HKEY root,
+    const base::Version& existing_version,
+    WorkItemList* list) {
+  DCHECK(list);
+  if (!GetDowngradeVersion(root).IsValid()) {
+    list->AddSetRegValueWorkItem(
+        root, BrowserDistribution::GetDistribution()->GetStateKey(),
+        KEY_WOW64_32KEY, kRegDowngradeVersion,
+        base::ASCIIToUTF16(existing_version.GetString()), false);
+  }
+}
+
+// static
+void InstallUtil::AddRemoveDowngradeVersionItem(
+    HKEY root,
+    const base::Version& new_version,
+    WorkItemList* list) {
+  DCHECK(list);
+  base::Version downgrade_version = GetDowngradeVersion(root);
+  if (downgrade_version.IsValid() && downgrade_version <= new_version) {
+    list->AddDeleteRegValueWorkItem(
+        root, BrowserDistribution::GetDistribution()->GetStateKey(),
+        KEY_WOW64_32KEY, kRegDowngradeVersion);
+  }
+}
+
 InstallUtil::ProgramCompare::ProgramCompare(const base::FilePath& path_to_match)
     : ProgramCompare(path_to_match, ComparisonType::FILE) {}
 
 InstallUtil::ProgramCompare::ProgramCompare(const base::FilePath& path_to_match,
                                             ComparisonType comparison_type)
     : path_to_match_(path_to_match),
       file_info_(),
       comparison_type_(comparison_type) {
   DCHECK(!path_to_match_.empty());
   if (!OpenForInfo(path_to_match_, &file_, comparison_type_)) {
@@ skipping 38 matching lines @@
 
   // Open the program and see if it references the expected file.
   base::File file;
   BY_HANDLE_FILE_INFORMATION info = {};
 
   return (OpenForInfo(path, &file, comparison_type_) && GetInfo(file, &info) &&
           info.dwVolumeSerialNumber == file_info_.dwVolumeSerialNumber &&
           info.nFileIndexHigh == file_info_.nFileIndexHigh &&
           info.nFileIndexLow == file_info_.nFileIndexLow);
 }