AppCache: Enable scope checks by default

Bug: 999001
Change-Id: If3ec271dcec5b479a183c8a3a1da822e86f4e976
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1994415
Auto-Submit: Chase Phillips <cmp@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#730190}

content/browser/appcache/appcache_update_job.cc

@@ -207,7 +207,7 @@ int64_t ComputeAppCacheResponsePadding(const GURL& response_url,
 }  // namespace
 
 const base::Feature kAppCacheManifestScopeChecksFeature{
-    "AppCacheManifestScopeChecks", base::FEATURE_DISABLED_BY_DEFAULT};
+    "AppCacheManifestScopeChecks", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Helper class for collecting hosts per frontend when sending notifications
 // so that only one notification is sent for all hosts using the same frontend.