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

1 files changed, 8 insertions, 8 deletions

diff --git a/sync/util/cryptographer.cc b/sync/util/cryptographer.cc
index 61b5e63..0fed51e 100644
--- a/sync/util/cryptographer.cc
+++ b/sync/util/cryptographer.cc
@@ -110,12 +110,12 @@ std::string Cryptographer::DecryptToString(
   NigoriMap::const_iterator it = nigoris_.find(encrypted.key_name());
   if (nigoris_.end() == it) {
     NOTREACHED() << "Cannot decrypt message";
-    return std::string("");  // Caller should have called CanDecrypt(encrypt).
+    return std::string();  // Caller should have called CanDecrypt(encrypt).
   }
 
   std::string plaintext;
   if (!it->second->Decrypt(encrypted.blob(), &plaintext)) {
-    return std::string("");
+    return std::string();
   }
 
   return plaintext;
@@ -271,18 +271,18 @@ bool Cryptographer::GetBootstrapToken(std::string* token) const {
 std::string Cryptographer::UnpackBootstrapToken(
     const std::string& token) const {
   if (token.empty())
-    return "";
+    return std::string();
 
   std::string encrypted_data;
   if (!base::Base64Decode(token, &encrypted_data)) {
     DLOG(WARNING) << "Could not decode token.";
-    return "";
+    return std::string();
   }
 
   std::string unencrypted_token;
   if (!encryptor_->DecryptString(encrypted_data, &unencrypted_token)) {
     DLOG(WARNING) << "Decryption of bootstrap token failed.";
-    return "";
+    return std::string();
   }
   return unencrypted_token;
 }
@@ -328,15 +328,15 @@ bool Cryptographer::KeybagIsStale(
 
 std::string Cryptographer::GetDefaultNigoriKey() const {
   if (!is_initialized())
-    return "";
+    return std::string();
   NigoriMap::const_iterator iter = nigoris_.find(default_nigori_name_);
   if (iter == nigoris_.end())
-    return "";
+    return std::string();
   sync_pb::NigoriKey key;
   if (!iter->second->ExportKeys(key.mutable_user_key(),
                                 key.mutable_encryption_key(),
                                 key.mutable_mac_key()))
-    return "";
+    return std::string();
   return key.SerializeAsString();
 }