update_engine: use new base::Delete{File,PathRecursively}

base::DeleteFile(const FilePath& path, bool recursive) would be
deprecated in next libchrome uprev.

BUG=chromium:1144735
TEST=cros_run_unit_tests --board=eve --packages update_engine

Change-Id: Iaeac97f533a156c2c29f7ba53755664d6591b0a1
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2543515
Tested-by: Grace Cham <hscham@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Grace Cham <hscham@chromium.org>
diff --git a/common/prefs.cc b/common/prefs.cc
index 52a58b7..84fe536 100644
--- a/common/prefs.cc
+++ b/common/prefs.cc
@@ -41,7 +41,11 @@
        dir_path = path_enum.Next()) {
     DeleteEmptyDirectories(dir_path);
     if (base::IsDirectoryEmpty(dir_path))
+#if BASE_VER < 800000
       base::DeleteFile(dir_path, false);
+#else
+      base::DeleteFile(dir_path);
+#endif
   }
 }
 
@@ -210,7 +214,11 @@
 bool Prefs::FileStorage::DeleteKey(const string& key) {
   base::FilePath filename;
   TEST_AND_RETURN_FALSE(GetFileNameForKey(key, &filename));
+#if BASE_VER < 800000
   TEST_AND_RETURN_FALSE(base::DeleteFile(filename, false));
+#else
+  TEST_AND_RETURN_FALSE(base::DeleteFile(filename));
+#endif
   return true;
 }