Add best-effort/allow rollback flags on WorkItem.

chrome/installer/setup/install_worker.cc

Index: chrome/installer/setup/install_worker.cc
diff --git a/chrome/installer/setup/install_worker.cc b/chrome/installer/setup/install_worker.cc
index 5878c00439e338b422250972c0fa50ccb7bf8aa1..9aae50ff2bcbbfbb5a42690b011b48cf1fff1260 100644
--- a/chrome/installer/setup/install_worker.cc
+++ b/chrome/installer/setup/install_worker.cc
@@ -272,7 +272,7 @@ void AddDeleteUninstallEntryForMSIWorkItems(
 
   WorkItem* delete_reg_key = work_item_list->AddDeleteRegKeyWorkItem(
       reg_root, uninstall_reg, KEY_WOW64_32KEY);
-  delete_reg_key->set_ignore_failure(true);
+  delete_reg_key->set_best_effort(true);
 }
 
 // Adds Chrome specific install work items to |install_list|.
@@ -289,17 +289,20 @@ void AddChromeWorkItems(const InstallationState& original_state,
   const base::FilePath& target_path = installer_state.target_path();
 
   if (current_version) {
-    // Delete the archive from an existing install to save some disk space.  We
-    // make this an unconditional work item since there's no need to roll this
-    // back; if installation fails we'll be moved to the "-full" channel anyway.
+    // Delete the archive from an existing install to save some disk space.
     base::FilePath old_installer_dir(
         installer_state.GetInstallerDirectory(*current_version));
     base::FilePath old_archive(
         old_installer_dir.Append(installer::kChromeArchive));
     // Don't delete the archive that we are actually installing from.
     if (archive_path != old_archive) {
-      install_list->AddDeleteTreeWorkItem(old_archive, temp_path)->
-          set_ignore_failure(true);
+      auto* delete_old_archive_work_item =
+          install_list->AddDeleteTreeWorkItem(old_archive, temp_path);
+      // Don't cause failure of |install_list| if this WorkItem fails.
+      delete_old_archive_work_item->set_best_effort(true);
+      // No need to roll this back; if installation fails we'll be moved to the
+      // "-full" channel anyway.

[fdoray, 2016/04/14 14:24:34]

I don't understand what this comment means.

[grt (UTC plus 2), 2016/04/14 15:47:02]

'No need to roll this back...'
The uncompressed archive of the current version of Chrome must be present
on-disk to support differential updates. When multiple old versions are present
(think of successive in-use updates: N is in-use, N+1, N+2, and N+3 have been
installed), the uncompressed archives from the older version(s) can be deleted
because they won't be used as the basis for future diff updates (only N3 will be
in the case above).

'...the "-full" channel...'
This is referring to a contract between the update server and the installer.
mini_installer.exe appends "-full" to Chrome's "additional parameters" reg value
before running setup.exe. the update server will unconditionally deliver a full
(rather than a diff) update if this suffix is present. So if this install fails
for other reasons, we don't need to roll-back the deletion of the uncompressed
archive since the next update is guaranteed to be a full rather than a diff
update.

+      delete_old_archive_work_item->set_allow_rollback(false);
     }
   }
 
@@ -374,9 +377,10 @@ void AddChromeWorkItems(const InstallationState& original_state,
                              WorkItem::ALWAYS_MOVE);
 
   // Delete any old_chrome.exe if present (ignore failure if it's in use).
-  install_list->AddDeleteTreeWorkItem(
-      target_path.Append(installer::kChromeOldExe), temp_path)->
-          set_ignore_failure(true);
+  install_list
+      ->AddDeleteTreeWorkItem(target_path.Append(installer::kChromeOldExe),
+                              temp_path)
+      ->set_best_effort(true);
 }
 
 // Adds work items to remove COM registration for |product|'s deprecated
@@ -1145,7 +1149,7 @@ void AddRegisterComDllWorkItems(const base::FilePath& dll_folder,
                                 const std::vector<base::FilePath>& dll_list,
                                 bool system_level,
                                 bool do_register,
-                                bool ignore_failures,
+                                bool best_effort,
                                 WorkItemList* work_item_list) {
   DCHECK(work_item_list);
   if (dll_list.empty()) {
@@ -1157,7 +1161,7 @@ void AddRegisterComDllWorkItems(const base::FilePath& dll_folder,
       WorkItem* work_item = work_item_list->AddSelfRegWorkItem(
           dll_path.value(), do_register, !system_level);
       DCHECK(work_item);
-      work_item->set_ignore_failure(ignore_failures);
+      work_item->set_best_effort(best_effort);
     }
   }
 }
@@ -1176,7 +1180,7 @@ void AddSetMsiMarkerWorkItem(const InstallerState& installer_state,
                                              msi_value,
                                              true);
   DCHECK(set_msi_work_item);
-  set_msi_work_item->set_ignore_failure(true);
+  set_msi_work_item->set_best_effort(true);
   set_msi_work_item->set_log_message("Could not write MSI marker!");
 }