Fixed OSX crash in net::URLFetcherCore::URLFetcherCore

chrome/browser/local_discovery/privet_url_fetcher.cc

Index: chrome/browser/local_discovery/privet_url_fetcher.cc
diff --git a/chrome/browser/local_discovery/privet_url_fetcher.cc b/chrome/browser/local_discovery/privet_url_fetcher.cc
index 832bd43ae3986b0e59f6655cbd9d5b202fd36654..6208e8d770917ab0b5522b9809a8d9c96d35e018 100644
--- a/chrome/browser/local_discovery/privet_url_fetcher.cc
+++ b/chrome/browser/local_discovery/privet_url_fetcher.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include "base/bind.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/json/json_reader.h"
 #include "base/location.h"
 #include "base/memory/singleton.h"
@@ -211,6 +212,12 @@ void PrivetURLFetcher::Try() {
 void PrivetURLFetcher::Start() {
   DCHECK_EQ(tries_, 0);  // We haven't called |Start()| yet.
 
+  if (!url_.is_valid()) {
+    // Not yet clear why it's possible. crbug.com/513505
+    base::debug::DumpWithoutCrashing();
+    return delegate_->OnError(this, UNKNOWN_ERROR);
+  }
+
   if (!send_empty_privet_token_ && !v3_mode_) {
     std::string privet_access_token;
     privet_access_token = GetPrivetAccessToken();