Adjust URLFetcher::Create API so that object is returned as scoped_ptr.

ios/chrome/browser/updatable_config/updatable_config_base.mm

Index: ios/chrome/browser/updatable_config/updatable_config_base.mm
diff --git a/ios/chrome/browser/updatable_config/updatable_config_base.mm b/ios/chrome/browser/updatable_config/updatable_config_base.mm
index b28fe21162e63887406008ffb31923d5382c8413..80c3ddb83fb36b810043a6a200e63428e672769d 100644
--- a/ios/chrome/browser/updatable_config/updatable_config_base.mm
+++ b/ios/chrome/browser/updatable_config/updatable_config_base.mm
@@ -57,7 +57,7 @@ class ConfigFetcher : public net::URLFetcherDelegate {
 
   // Starts fetching |url| for updated configuration.
   void Fetch(const GURL& url, net::URLRequestContextGetter* context) {
-    fetcher_.reset(net::URLFetcher::Create(url, net::URLFetcher::GET, this));
+    fetcher_ = net::URLFetcher::Create(url, net::URLFetcher::GET, this);
     fetcher_->SetRequestContext(context);
     fetcher_->Start();
   }