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

ios/chrome/browser/net/image_fetcher.mm

Index: ios/chrome/browser/net/image_fetcher.mm
diff --git a/ios/chrome/browser/net/image_fetcher.mm b/ios/chrome/browser/net/image_fetcher.mm
index 89f59c7dc138c406529002d615a070cc405ae5ad..edf205cdc46046e12b8888eeeaf1bf60004f5c29 100644
--- a/ios/chrome/browser/net/image_fetcher.mm
+++ b/ios/chrome/browser/net/image_fetcher.mm
@@ -83,9 +83,8 @@ void ImageFetcher::StartDownload(
     const std::string& referrer,
     net::URLRequest::ReferrerPolicy referrer_policy) {
   DCHECK(request_context_getter_.get());
-  net::URLFetcher* fetcher = net::URLFetcher::Create(url,
-                                                     net::URLFetcher::GET,
-                                                     this);
+  net::URLFetcher* fetcher =
+      net::URLFetcher::Create(url, net::URLFetcher::GET, this).release();
   downloads_in_progress_[fetcher] = [callback copy];
   fetcher->SetLoadFlags(
       net::LOAD_DO_NOT_SEND_COOKIES | net::LOAD_DO_NOT_SAVE_COOKIES |