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

This patch was generated by running the empty_string clang tool
across the Chromium Linux compilation database. Implicitly or
explicitly constructing std::string() with a "" argument is
inefficient as the caller needs to emit extra instructions to
pass an argument, and the constructor needlessly copies a byte
into internal storage. Rewriting these instances to simply call
the default constructor appears to save ~14-18 kilobytes on an
optimized release build.

BUG=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=193020

Review URL: https://codereview.chromium.org/13145003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193040 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 2 insertions, 3 deletions

diff --git a/chrome/browser/web_applications/web_app_unittest.cc b/chrome/browser/web_applications/web_app_unittest.cc
index 0bd1c01..149f62b 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);
 }