Disallow packing or loading unpacked manifest v1 extensions.

chrome/browser/extensions/extension_browsertest.h

Index: chrome/browser/extensions/extension_browsertest.h
diff --git a/chrome/browser/extensions/extension_browsertest.h b/chrome/browser/extensions/extension_browsertest.h
index 06b67fba638c404c916d4ae56d2be840ffba3de7..aef8c36ab264057e59591d3ade0afc44587dcfea 100644
--- a/chrome/browser/extensions/extension_browsertest.h
+++ b/chrome/browser/extensions/extension_browsertest.h
@@ -37,7 +37,11 @@ class ExtensionBrowserTest : virtual public InProcessBrowserTest,
 
     // Don't fail when the loaded manifest has warnings (should only be used
     // when testing deprecated features).
-    kFlagIgnoreManifestWarnings = 1 << 2
+    kFlagIgnoreManifestWarnings = 1 << 2,
+
+    // Allow older manifest versions (typically these can't be loaded - we allow
+    // them for testing).
+    kFlagAllowOldManifestVersions = 1 << 3,
   };
 
   ExtensionBrowserTest();