Reland of place string::find(prefix) == 0 pattern with base::StartsWith().

chrome/browser/download/download_browsertest.cc

Index: chrome/browser/download/download_browsertest.cc
diff --git a/chrome/browser/download/download_browsertest.cc b/chrome/browser/download/download_browsertest.cc
index ca625e1f60eb2f93d69ea016b5d8100600b175da..fc6b5fbb1139b7dd8cba478d972dad4ef866b214 100644
--- a/chrome/browser/download/download_browsertest.cc
+++ b/chrome/browser/download/download_browsertest.cc
@@ -2558,8 +2558,10 @@
 EchoReferrerRequestHandler(const net::test_server::HttpRequest& request) {
   const std::string kReferrerHeader = "Referer";  // SIC
 
-  if (request.relative_url.find("/echoreferrer") != 0)
+  if (!base::StartsWith(request.relative_url, "/echoreferrer",
+                        base::CompareCase::SENSITIVE)) {
     return std::unique_ptr<net::test_server::HttpResponse>();
+  }
 
   std::unique_ptr<net::test_server::BasicHttpResponse> response(
       new net::test_server::BasicHttpResponse());