Add DCHECKs to validate ProfileIOData's list of protocols.

chrome/browser/net/chrome_url_request_context_getter.cc

Index: chrome/browser/net/chrome_url_request_context_getter.cc
diff --git a/chrome/browser/net/chrome_url_request_context_getter.cc b/chrome/browser/net/chrome_url_request_context_getter.cc
index e95e09eb00695de558590d5f7e3b7d0c3772aabb..9cf4f2deb057c8bb3578fd803c9d3bc4490cca2d 100644
--- a/chrome/browser/net/chrome_url_request_context_getter.cc
+++ b/chrome/browser/net/chrome_url_request_context_getter.cc
@@ -49,6 +49,10 @@ class FactoryForMain : public ChromeURLRequestContextFactory {
       : profile_io_data_(profile_io_data),
         request_interceptors_(std::move(request_interceptors)) {
     std::swap(protocol_handlers_, *protocol_handlers);
+#if DCHECK_IS_ON()
+    for (const auto& handler : protocol_handlers_)
+      DCHECK(ProfileIOData::IsBuiltInProtocol(handler.first));
+#endif
   }
 
   net::URLRequestContext* Create() override {