Support rollback with installerdata in mini_installer

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>
 
@@ skipping 166 matching lines @@
 // (typical new install), the function creates package during install
 // and removes the whole directory during rollback.
 installer::InstallStatus InstallNewVersion(
     const installer::InstallationState& original_state,
     const installer::InstallerState& installer_state,
     const base::FilePath& setup_path,
     const base::FilePath& archive_path,
     const base::FilePath& src_path,
     const base::FilePath& temp_path,
     const Version& new_version,
-    std::unique_ptr<Version>* current_version) {
+    std::unique_ptr<Version>* current_version,
+    bool is_downgrade_allowed) {
   DCHECK(current_version);
 
   installer_state.UpdateStage(installer::BUILDING);
 
   current_version->reset(installer_state.GetCurrentVersion(original_state));
   installer::SetCurrentVersionCrashKey(current_version->get());
 
   std::unique_ptr<WorkItemList> install_list(WorkItem::CreateWorkItemList());
 
   AddInstallWorkItems(original_state,
@@ skipping 31 matching lines @@
   if (!current_version->get()) {
     VLOG(1) << "First install of version " << new_version;
     return installer::FIRST_INSTALL_SUCCESS;
   }
 
   if (new_version == **current_version) {
     VLOG(1) << "Install repaired of version " << new_version;
     return installer::INSTALL_REPAIRED;
   }
 
+  bool new_chrome_exe_exists = base::PathExists(new_chrome_exe);
   if (new_version > **current_version) {
-    if (base::PathExists(new_chrome_exe)) {
+    if (new_chrome_exe_exists) {
       VLOG(1) << "Version updated to " << new_version
               << " while running " << **current_version;
       return installer::IN_USE_UPDATED;
     }
     VLOG(1) << "Version updated to " << new_version;
     return installer::NEW_VERSION_UPDATED;
   }
 
+  if (is_downgrade_allowed) {
+    if (new_chrome_exe_exists) {
+      VLOG(1) << "Version downgrade to " << new_version << " while running "

[grt (UTC plus 2), 2016/04/28 20:13:45]

"downgraded" sounds more better to me

[zmin, 2016/04/28 20:20:37]

Done.

+              << **current_version;
+      return installer::IN_USE_DOWNGRADE;
+    }
+    VLOG(1) << "Version downgrade to " << new_version;
+    return installer::OLD_VERSION_DOWNGRADE;
+  }
+
   LOG(ERROR) << "Not sure how we got here while updating"
              << ", new version: " << new_version
              << ", old version: " << **current_version;
 
   return installer::INSTALL_FAILED;
 }
 
 // Returns the number of components in |file_path|.
 size_t GetNumPathComponents(const base::FilePath& file_path) {
   std::vector<base::FilePath::StringType> components;
@@ skipping 316 matching lines @@
   LOG_IF(ERROR, !RemoveFromMovesPendingReboot(installer_state.target_path()))
       << "Error accessing pending moves value.";
 
   // Create VisualElementManifest.xml in |src_path| (if required) so that it
   // looks as if it had been extracted from the archive when calling
   // InstallNewVersion() below.
   installer_state.UpdateStage(installer::CREATING_VISUAL_MANIFEST);
   CreateVisualElementsManifest(src_path, new_version);
 
   std::unique_ptr<Version> existing_version;
-  InstallStatus result = InstallNewVersion(original_state, installer_state,
-      setup_path, archive_path, src_path, install_temp_path, new_version,
-      &existing_version);
+  InstallStatus result =
+      InstallNewVersion(original_state, installer_state, setup_path,
+                        archive_path, src_path, install_temp_path, new_version,
+                        &existing_version, IsDowngradeAllowed(prefs));
 
   // TODO(robertshield): Everything below this line should instead be captured
   // by WorkItems.
   if (!InstallUtil::GetInstallReturnCode(result)) {
     installer_state.UpdateStage(installer::UPDATING_CHANNELS);
 
     // Update the modifiers on the channel values for the product(s) being
     // installed and for the binaries in case of multi-install.
     installer_state.UpdateChannels();
 
@@ skipping 41 matching lines @@
 
       bool make_chrome_default = false;
       prefs.GetBool(master_preferences::kMakeChromeDefault,
                     &make_chrome_default);
 
       // If this is not the user's first Chrome install, but they have chosen
       // 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) {
+      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);
       }
 
       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());
@@ skipping 101 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