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

content/browser/loader/resource_handler.cc

Index: content/browser/loader/resource_handler.cc
diff --git a/content/browser/loader/resource_handler.cc b/content/browser/loader/resource_handler.cc
index 961934d05e9f37a9f1315ae2a8862402894d5aa7..0f875512f6956706607e8ecc09a5ab9db9e8e125 100644
--- a/content/browser/loader/resource_handler.cc
+++ b/content/browser/loader/resource_handler.cc
@@ -16,7 +16,9 @@ void ResourceHandler::SetDelegate(Delegate* delegate) {
   delegate_ = delegate;
 }
 
-ResourceHandler::~ResourceHandler() {}
+ResourceHandler::~ResourceHandler() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+}
 
 ResourceHandler::ResourceHandler(net::URLRequest* request)
     : request_(request) {}