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

2 files changed, 6 insertions, 5 deletions

diff --git a/crypto/ec_private_key_unittest.cc b/crypto/ec_private_key_unittest.cc
index a052a9a..d2ec256 100644
--- a/crypto/ec_private_key_unittest.cc
+++ b/crypto/ec_private_key_unittest.cc
@@ -23,7 +23,7 @@ TEST(ECPrivateKeyUnitTest, OpenSSLStub) {
 // back the same exact public key, and the private key should have the same
 // value and elliptic curve params.
 TEST(ECPrivateKeyUnitTest, InitRandomTest) {
-  const std::string password1 = "";
+  const std::string password1;
   const std::string password2 = "test";
 
   scoped_ptr<crypto::ECPrivateKey> keypair1(
@@ -86,7 +86,7 @@ TEST(ECPrivateKeyUnitTest, InitRandomTest) {
 }
 
 TEST(ECPrivateKeyUnitTest, BadPasswordTest) {
-  const std::string password1 = "";
+  const std::string password1;
   const std::string password2 = "test";
 
   scoped_ptr<crypto::ECPrivateKey> keypair1(
diff --git a/crypto/ec_signature_creator_unittest.cc b/crypto/ec_signature_creator_unittest.cc
index df73bec..b34022b 100644
--- a/crypto/ec_signature_creator_unittest.cc
+++ b/crypto/ec_signature_creator_unittest.cc
@@ -30,13 +30,14 @@ TEST(ECSignatureCreatorTest, BasicTest) {
   ASSERT_TRUE(key_original.get());
 
   std::vector<uint8> key_info;
-  ASSERT_TRUE(key_original->ExportEncryptedPrivateKey("", 1000, &key_info));
+  ASSERT_TRUE(
+      key_original->ExportEncryptedPrivateKey(std::string(), 1000, &key_info));
   std::vector<uint8> pubkey_info;
   ASSERT_TRUE(key_original->ExportPublicKey(&pubkey_info));
 
   scoped_ptr<crypto::ECPrivateKey> key(
-      crypto::ECPrivateKey::CreateFromEncryptedPrivateKeyInfo("", key_info,
-                                                              pubkey_info));
+      crypto::ECPrivateKey::CreateFromEncryptedPrivateKeyInfo(
+          std::string(), key_info, pubkey_info));
   ASSERT_TRUE(key.get());
   ASSERT_TRUE(key->key() != NULL);