Rewrite std::string("") to std::string(), Linux edition.

chrome/browser/web_applications/web_app_unittest.cc

Index: chrome/browser/web_applications/web_app_unittest.cc
diff --git a/chrome/browser/web_applications/web_app_unittest.cc b/chrome/browser/web_applications/web_app_unittest.cc
index 0bd1c01a4b9152439d618c2cfa31bf76ff5f7cef..149f62b9b73c6a98952016e5856c5473cbf76e39 100644
--- a/chrome/browser/web_applications/web_app_unittest.cc
+++ b/chrome/browser/web_applications/web_app_unittest.cc
@@ -71,9 +71,8 @@ TEST_F(WebApplicationTest, AppDirWithId) {
 TEST_F(WebApplicationTest, AppDirWithUrl) {
   base::FilePath profile_path(FILE_PATH_LITERAL("profile"));
   base::FilePath result(web_app::GetWebAppDataDirectory(
-      profile_path, "", GURL("http://example.com")));
+      profile_path, std::string(), GURL("http://example.com")));
   base::FilePath expected = profile_path.AppendASCII("Web Applications")
-                                  .AppendASCII("example.com")
-                                  .AppendASCII("http_80");
+      .AppendASCII("example.com").AppendASCII("http_80");
   EXPECT_EQ(expected, result);
 }