Add detailed histograms for DownloadProtectionService URLFetcher errors.

chrome/browser/ui/webui/net_internals/net_internals_ui.cc

Index: chrome/browser/ui/webui/net_internals/net_internals_ui.cc
diff --git a/chrome/browser/ui/webui/net_internals/net_internals_ui.cc b/chrome/browser/ui/webui/net_internals/net_internals_ui.cc
index e896dfa9e996007cd2ebbf03b6f99d8e6e729755..cea71534cf6a2cba5dc8a7947c9293e9948f72e6 100644
--- a/chrome/browser/ui/webui/net_internals/net_internals_ui.cc
+++ b/chrome/browser/ui/webui/net_internals/net_internals_ui.cc
@@ -189,6 +189,9 @@ Value* RequestStateToValue(const net::URLRequest* request,
     case net::URLRequestStatus::FAILED:
       dict->SetString("status", "FAILED");
       break;
+    case net::URLRequestStatus::STATUS_MAX:
+      NOTREACHED();
+      break;
   }
   if (request->status().error() != net::OK)
     dict->SetInteger("net_error", request->status().error());