PreloadCheck class for extension pre-install checks

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index c28aaf30cd0ef826be45eab2aa6bbdfe84da3e0f..6c57bc0503e7e3034f0db29ad8b0549f9cebb547 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -3516,6 +3516,7 @@ test("unit_tests") {
     "//device/base:mocks",
     "//device/bluetooth:mocks",
     "//device/usb:test_support",
+    "//extensions/browser:test_support",
     "//extensions/features",
     "//google_apis",
     "//gpu:test_support",
@@ -3911,6 +3912,7 @@ test("unit_tests") {
       "../browser/extensions/api/web_request/web_request_event_details_unittest.cc",
       "../browser/extensions/api/web_request/web_request_permissions_unittest.cc",
       "../browser/extensions/app_data_migrator_unittest.cc",
+      "../browser/extensions/blacklist_check_unittest.cc",
       "../browser/extensions/blacklist_state_fetcher_unittest.cc",
       "../browser/extensions/bookmark_app_helper_unittest.cc",
       "../browser/extensions/chrome_app_sorting_unittest.cc",