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 9072029d2cfffc7578cb9b50312c2b9e6e699022..72e28cb49013b9bba24c3f4be6fabf17b49ae6c4 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -3514,6 +3514,7 @@ test("unit_tests") {
     "//device/base:mocks",
     "//device/bluetooth:mocks",
     "//device/usb:test_support",
+    "//extensions/browser:test_support",
     "//extensions/features",
     "//google_apis",
     "//gpu:test_support",
@@ -3910,6 +3911,7 @@ 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",
@@ -4510,9 +4512,8 @@ test("unit_tests") {
       "//third_party/ocmock",
     ]
 
-    sources += [
-      "../browser/ui/cocoa/applescript/apple_event_util_unittest.mm",
-    ]
+    sources +=
+        [ "../browser/ui/cocoa/applescript/apple_event_util_unittest.mm" ]
 
     if (mac_views_browser) {
       # TODO(tapted): Add chrome_unit_tests_views_non_mac_sources.