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

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

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193020 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 13 insertions, 11 deletions

diff --git a/chrome/browser/browsing_data/browsing_data_cookie_helper_unittest.cc b/chrome/browser/browsing_data/browsing_data_cookie_helper_unittest.cc
index 94df56c..be0879b 100644
--- a/chrome/browser/browsing_data/browsing_data_cookie_helper_unittest.cc
+++ b/chrome/browser/browsing_data/browsing_data_cookie_helper_unittest.cc
@@ -277,8 +277,10 @@ TEST_F(BrowsingDataCookieHelperTest, CannedDomainCookie) {
   helper->AddChangedCookie(origin, origin, "A=1; Domain=.www.google.com",
                            net::CookieOptions());
   // Try adding invalid cookies that will be ignored.
-  helper->AddChangedCookie(origin, origin, "", net::CookieOptions());
-  helper->AddChangedCookie(origin, origin, "C=bad guy; Domain=wrongdomain.com",
+  helper->AddChangedCookie(origin, origin, std::string(), net::CookieOptions());
+  helper->AddChangedCookie(origin,
+                           origin,
+                           "C=bad guy; Domain=wrongdomain.com",
                            net::CookieOptions());
 
   helper->StartFetching(
diff --git a/chrome/browser/browsing_data/browsing_data_database_helper_browsertest.cc b/chrome/browser/browsing_data/browsing_data_database_helper_browsertest.cc
index 8c29d07..019a45b 100644
--- a/chrome/browser/browsing_data/browsing_data_database_helper_browsertest.cc
+++ b/chrome/browser/browsing_data/browsing_data_database_helper_browsertest.cc
@@ -104,9 +104,9 @@ IN_PROC_BROWSER_TEST_F(BrowsingDataDatabaseHelperTest, CannedAddDatabase) {
 
   scoped_refptr<CannedBrowsingDataDatabaseHelper> helper(
       new CannedBrowsingDataDatabaseHelper(browser()->profile()));
-  helper->AddDatabase(origin1, db1, "");
-  helper->AddDatabase(origin1, db2, "");
-  helper->AddDatabase(origin2, db3, "");
+  helper->AddDatabase(origin1, db1, std::string());
+  helper->AddDatabase(origin1, db2, std::string());
+  helper->AddDatabase(origin2, db3, std::string());
 
   TestCompletionCallback callback;
   helper->StartFetching(
@@ -136,8 +136,8 @@ IN_PROC_BROWSER_TEST_F(BrowsingDataDatabaseHelperTest, CannedUnique) {
 
   scoped_refptr<CannedBrowsingDataDatabaseHelper> helper(
       new CannedBrowsingDataDatabaseHelper(browser()->profile()));
-  helper->AddDatabase(origin, db, "");
-  helper->AddDatabase(origin, db, "");
+  helper->AddDatabase(origin, db, std::string());
+  helper->AddDatabase(origin, db, std::string());
 
   TestCompletionCallback callback;
   helper->StartFetching(
diff --git a/chrome/browser/browsing_data/browsing_data_database_helper_unittest.cc b/chrome/browser/browsing_data/browsing_data_database_helper_unittest.cc
index 2a2b474..89c290d 100644
--- a/chrome/browser/browsing_data/browsing_data_database_helper_unittest.cc
+++ b/chrome/browser/browsing_data/browsing_data_database_helper_unittest.cc
@@ -35,7 +35,7 @@ TEST_F(CannedBrowsingDataDatabaseHelperTest, Empty) {
       new CannedBrowsingDataDatabaseHelper(&profile));
 
   ASSERT_TRUE(helper->empty());
-  helper->AddDatabase(origin, db, "");
+  helper->AddDatabase(origin, db, std::string());
   ASSERT_FALSE(helper->empty());
   helper->Reset();
   ASSERT_TRUE(helper->empty());
@@ -52,9 +52,9 @@ TEST_F(CannedBrowsingDataDatabaseHelperTest, IgnoreExtensionsAndDevTools) {
       new CannedBrowsingDataDatabaseHelper(&profile));
 
   ASSERT_TRUE(helper->empty());
-  helper->AddDatabase(origin1, db, "");
+  helper->AddDatabase(origin1, db, std::string());
   ASSERT_TRUE(helper->empty());
-  helper->AddDatabase(origin2, db, "");
+  helper->AddDatabase(origin2, db, std::string());
   ASSERT_TRUE(helper->empty());
   helper->Reset();
   ASSERT_TRUE(helper->empty());
diff --git a/chrome/browser/browsing_data/cookies_tree_model_unittest.cc b/chrome/browser/browsing_data/cookies_tree_model_unittest.cc
index 58b1dd5..9699414 100644
--- a/chrome/browser/browsing_data/cookies_tree_model_unittest.cc
+++ b/chrome/browser/browsing_data/cookies_tree_model_unittest.cc
@@ -416,7 +416,7 @@ TEST_F(CookiesTreeModelTest, RemoveAll) {
     SCOPED_TRACE("After removing");
     EXPECT_EQ(1, cookies_model->GetRoot()->GetTotalNodeCount());
     EXPECT_EQ(0, cookies_model->GetRoot()->child_count());
-    EXPECT_EQ(std::string(""), GetDisplayedCookies(cookies_model.get()));
+    EXPECT_EQ(std::string(), GetDisplayedCookies(cookies_model.get()));
     EXPECT_TRUE(mock_browsing_data_cookie_helper_->AllDeleted());
     EXPECT_TRUE(mock_browsing_data_database_helper_->AllDeleted());
     EXPECT_TRUE(mock_browsing_data_local_storage_helper_->AllDeleted());