Revert "Revert "AU: do not copy filesystem during full updates""

This reverts commit d1cd325c3135d88498483da811b594ba6b91ce42

The problem that caused all autotests to fail with the original CL has now been rectified; lab devservers were updated to send the correct delta flag in their omaha response.

Change-Id: I664afb33f72856572baaa658cbd473c07271af36
Reviewed-on: https://gerrit.chromium.org/gerrit/56600
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/filesystem_copier_action.cc b/filesystem_copier_action.cc
index 7024b67..3e5160e 100644
--- a/filesystem_copier_action.cc
+++ b/filesystem_copier_action.cc
@@ -69,8 +69,11 @@
     return;
   }
   install_plan_ = GetInputObject();
-  if (!verify_hash_ && install_plan_.is_resume) {
+  if (!verify_hash_ &&
+      (install_plan_.is_resume || install_plan_.is_full_update)) {
     // No copy or hash verification needed. Done!
+    LOG(INFO) << "filesystem copying skipped: "
+              << (install_plan_.is_resume ? "resumed" : "full") << " update";
     if (HasOutputPipe())
       SetOutputObject(install_plan_);
     abort_action_completer.set_code(kErrorCodeSuccess);