Replace deprecated base::NonThreadSafe in content/browser/appcache in favor of SequenceChecker.

content/browser/appcache/appcache_job.cc

Index: content/browser/appcache/appcache_job.cc
diff --git a/content/browser/appcache/appcache_job.cc b/content/browser/appcache/appcache_job.cc
index 27a5897298f9aef2f51c2c5714d95333554a012a..271553f6bfdc3c66adc1a330c198a8a5d8be9cdd 100644
--- a/content/browser/appcache/appcache_job.cc
+++ b/content/browser/appcache/appcache_job.cc
@@ -32,7 +32,9 @@ std::unique_ptr<AppCacheJob> AppCacheJob::Create(
   return job;
 }
 
-AppCacheJob::~AppCacheJob() {}
+AppCacheJob::~AppCacheJob() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+}
 
 base::WeakPtr<AppCacheJob> AppCacheJob::GetWeakPtr() {
   return weak_factory_.GetWeakPtr();