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

components/precache/core/precache_fetcher.cc

Index: components/precache/core/precache_fetcher.cc
diff --git a/components/precache/core/precache_fetcher.cc b/components/precache/core/precache_fetcher.cc
index 49f84a216ec7c27a366269b51b83a65cb2cc9b38..b6e75afcfdf1c34c03753005cd138f4dc8758613 100644
--- a/components/precache/core/precache_fetcher.cc
+++ b/components/precache/core/precache_fetcher.cc
@@ -121,7 +121,7 @@ PrecacheFetcher::Fetcher::Fetcher(
     net::URLRequestContextGetter* request_context, const GURL& url,
     const base::Callback<void(const URLFetcher&)>& callback)
     : callback_(callback) {
-  url_fetcher_.reset(URLFetcher::Create(url, URLFetcher::GET, this));
+  url_fetcher_ = URLFetcher::Create(url, URLFetcher::GET, this);
   url_fetcher_->SetRequestContext(request_context);
   url_fetcher_->Start();
 }