Replace ToLower calls to the new format

Replaces
  base::StringToLowerASCII(string)
with
  base::ToLowerASCII(string)
This form is 1:1 search and replace.

A bunch of places did something like this:
  std::string foo(something_else);
  base::StringToLowerASCII(&foo);
which became:
  foo = base::ToLowerASCII(something_else);

A couple places really wanted in-place changing and they became:
  foo = base::ToLowerASCII(foo);

There was pretty trivial cleanup in chrome_main_delegate.cc chrome/test/chromedriver/server/http_handler.cc (fix indenting).

There was more cleanup in:
chrome/installer/util/language_selector.cc and components/plugins/renderer/mobile_youtube_plugin.cc

In components/history/core/browser/url_utils.cc I removed the call since it was calling ToLower on the host name out of a GURL, which is already guaranteed to be lower-case.

NOPRESUBMIT=true
(due to touching code with wstrings)

Review URL: https://codereview.chromium.org/1279123004

Cr-Commit-Position: refs/heads/master@{#342659}

72 files changed, 107 insertions, 129 deletions

diff --git a/android_webview/browser/aw_content_browser_client.cc b/android_webview/browser/aw_content_browser_client.cc
index efbbdbe..1f59823 100644
--- a/android_webview/browser/aw_content_browser_client.cc
+++ b/android_webview/browser/aw_content_browser_client.cc
@@ -118,7 +118,7 @@ std::string AwContentBrowserClient::GetAcceptLangsImpl() {
 
   // If we're not en-US, add in en-US which will be
   // used with a lower q-value.
-  if (base::StringToLowerASCII(langs) != "en-us") {
+  if (base::ToLowerASCII(langs) != "en-us") {
     langs += ",en-US";
   }
   return langs;
diff --git a/base/command_line.cc b/base/command_line.cc
index 95ff644..c2ce33d 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -267,7 +267,7 @@ void CommandLine::SetProgram(const FilePath& program) {
 }
 
 bool CommandLine::HasSwitch(const base::StringPiece& switch_string) const {
-  DCHECK_EQ(StringToLowerASCII(switch_string.as_string()), switch_string);
+  DCHECK_EQ(ToLowerASCII(switch_string), switch_string);
   return switches_by_stringpiece_.find(switch_string) !=
          switches_by_stringpiece_.end();
 }
@@ -297,7 +297,7 @@ FilePath CommandLine::GetSwitchValuePath(
 
 CommandLine::StringType CommandLine::GetSwitchValueNative(
     const base::StringPiece& switch_string) const {
-  DCHECK_EQ(StringToLowerASCII(switch_string.as_string()), switch_string);
+  DCHECK_EQ(ToLowerASCII(switch_string), switch_string);
   auto result = switches_by_stringpiece_.find(switch_string);
   return result == switches_by_stringpiece_.end() ? StringType()
                                                   : *(result->second);
@@ -315,7 +315,7 @@ void CommandLine::AppendSwitchPath(const std::string& switch_string,
 void CommandLine::AppendSwitchNative(const std::string& switch_string,
                                      const CommandLine::StringType& value) {
 #if defined(OS_WIN)
-  const std::string switch_key = StringToLowerASCII(switch_string);
+  const std::string switch_key = ToLowerASCII(switch_string);
   StringType combined_switch_string(ASCIIToUTF16(switch_key));
 #elif defined(OS_POSIX)
   const std::string& switch_key = switch_string;
diff --git a/base/i18n/rtl.cc b/base/i18n/rtl.cc
index 25a9cfd..93f91c2 100644
--- a/base/i18n/rtl.cc
+++ b/base/i18n/rtl.cc
@@ -36,11 +36,8 @@ std::string GetLocaleString(const icu::Locale& locale) {
     result += country;
   }
 
-  if (variant != NULL && *variant != '\0') {
-    std::string variant_str(variant);
-    base::StringToLowerASCII(&variant_str);
-    result += '@' + variant_str;
-  }
+  if (variant != NULL && *variant != '\0')
+    result += '@' + base::ToLowerASCII(variant);
 
   return result;
 }
diff --git a/chrome/app/chrome_main_delegate.cc b/chrome/app/chrome_main_delegate.cc
index 031a0a1..254eae0 100644
--- a/chrome/app/chrome_main_delegate.cc
+++ b/chrome/app/chrome_main_delegate.cc
@@ -152,13 +152,11 @@ namespace {
 // Early versions of Chrome incorrectly registered a chromehtml: URL handler,
 // which gives us nothing but trouble. Avoid launching chrome this way since
 // some apps fail to properly escape arguments.
-bool HasDeprecatedArguments(const std::wstring& command_line) {
+bool HasDeprecatedArguments(const base::string16& command_line) {
   const wchar_t kChromeHtml[] = L"chromehtml:";
-  std::wstring command_line_lower = command_line;
+  base::string16 command_line_lower = base::ToLowerASCII(command_line);
   // We are only searching for ASCII characters so this is OK.
-  base::StringToLowerASCII(&command_line_lower);
-  std::wstring::size_type pos = command_line_lower.find(kChromeHtml);
-  return (pos != std::wstring::npos);
+  return (command_line_lower.find(kChromeHtml) != base::string16::npos);
 }
 
 // If we try to access a path that is not currently available, we want the call
diff --git a/chrome/app/signature_validator_win.cc b/chrome/app/signature_validator_win.cc
index e64446d..d4f86f0 100644
--- a/chrome/app/signature_validator_win.cc
+++ b/chrome/app/signature_validator_win.cc
@@ -39,8 +39,7 @@ bool ExtractPublicKeyHash(const CERT_CONTEXT* cert_context,
       crypt_blob.pbData), crypt_blob.cbData);
   crypto::SHA256HashString(key_bytes, hash, crypto::kSHA256Length);
 
-  *public_key_hash =
-      base::StringToLowerASCII(base::HexEncode(hash, arraysize(hash)));
+  *public_key_hash = base::ToLowerASCII(base::HexEncode(hash, arraysize(hash)));
   return true;
 }
 
diff --git a/chrome/app/signature_validator_win_unittest.cc b/chrome/app/signature_validator_win_unittest.cc
index 89cbda4..37408a7 100644
--- a/chrome/app/signature_validator_win_unittest.cc
+++ b/chrome/app/signature_validator_win_unittest.cc
@@ -85,7 +85,7 @@ class SignatureValidatorTest : public testing::Test {
     crypto::SHA256HashString(key_bytes, hash, crypto::kSHA256Length);
 
     std::string public_key_hash =
-        base::StringToLowerASCII(base::HexEncode(hash, arraysize(hash)));
+        base::ToLowerASCII(base::HexEncode(hash, arraysize(hash)));
     expected_hashes_.push_back(public_key_hash);
   }
 
diff --git a/chrome/browser/chromeos/customization/customization_document.cc b/chrome/browser/chromeos/customization/customization_document.cc
index 22e19268..780ba16 100644
--- a/chrome/browser/chromeos/customization/customization_document.cc
+++ b/chrome/browser/chromeos/customization/customization_document.cc
@@ -514,7 +514,7 @@ void ServicesCustomizationDocument::StartFetching() {
                                       &customization_id) &&
         !customization_id.empty()) {
       url_ = GURL(base::StringPrintf(
-          kManifestUrl, base::StringToLowerASCII(customization_id).c_str()));
+          kManifestUrl, base::ToLowerASCII(customization_id).c_str()));
     } else {
       // Remember that there is no customization ID in VPD.
       OnCustomizationNotFound();
diff --git a/chrome/browser/chromeos/file_manager/file_tasks.cc b/chrome/browser/chromeos/file_manager/file_tasks.cc
index 73757b3..4a01c08 100644
--- a/chrome/browser/chromeos/file_manager/file_tasks.cc
+++ b/chrome/browser/chromeos/file_manager/file_tasks.cc
@@ -169,7 +169,7 @@ void UpdateDefaultTask(PrefService* pref_service,
         iter != suffixes.end(); ++iter) {
       base::StringValue* value = new base::StringValue(task_id);
       // Suffixes are case insensitive.
-      std::string lower_suffix = base::StringToLowerASCII(*iter);
+      std::string lower_suffix = base::ToLowerASCII(*iter);
       mime_type_pref->SetWithoutPathExpansion(lower_suffix, value);
     }
   }
@@ -197,7 +197,7 @@ std::string GetDefaultTaskIdFromPrefs(const PrefService& pref_service,
       pref_service.GetDictionary(prefs::kDefaultTasksBySuffix);
   DCHECK(suffix_task_prefs);
   LOG_IF(ERROR, !suffix_task_prefs) << "Unable to open suffix prefs";
-  std::string lower_suffix = base::StringToLowerASCII(suffix);
+  std::string lower_suffix = base::ToLowerASCII(suffix);
   if (suffix_task_prefs)
     suffix_task_prefs->GetStringWithoutPathExpansion(lower_suffix, &task_id);
   VLOG_IF(1, !task_id.empty()) << "Found suffix default handler: " << task_id;
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index 926d0d51..86e899f 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -1145,7 +1145,7 @@ void UserSessionManager::InitializeStartUrls() const {
       const char* url = kChromeVoxTutorialURLPattern;
       PrefService* prefs = g_browser_process->local_state();
       const std::string current_locale =
-          base::StringToLowerASCII(prefs->GetString(prefs::kApplicationLocale));
+          base::ToLowerASCII(prefs->GetString(prefs::kApplicationLocale));
       std::string vox_url = base::StringPrintf(url, current_locale.c_str());
       start_urls.push_back(vox_url);
       can_show_getstarted_guide = false;
diff --git a/chrome/browser/chromeos/login/supervised/supervised_user_authentication.cc b/chrome/browser/chromeos/login/supervised/supervised_user_authentication.cc
index b4a64a3..389dcc5 100644
--- a/chrome/browser/chromeos/login/supervised/supervised_user_authentication.cc
+++ b/chrome/browser/chromeos/login/supervised/supervised_user_authentication.cc
@@ -40,9 +40,8 @@ const int kMasterKeySize = 32;
 std::string CreateSalt() {
     char result[kSaltSize];
     crypto::RandBytes(&result, sizeof(result));
-    return base::StringToLowerASCII(base::HexEncode(
-        reinterpret_cast<const void*>(result),
-        sizeof(result)));
+    return base::ToLowerASCII(
+        base::HexEncode(reinterpret_cast<const void*>(result), sizeof(result)));
 }
 
 std::string BuildRawHMACKey() {
@@ -164,7 +163,7 @@ bool SupervisedUserAuthentication::FillDataForNewUser(
 std::string SupervisedUserAuthentication::GenerateMasterKey() {
   char master_key_bytes[kMasterKeySize];
   crypto::RandBytes(&master_key_bytes, sizeof(master_key_bytes));
-  return base::StringToLowerASCII(
+  return base::ToLowerASCII(
       base::HexEncode(reinterpret_cast<const void*>(master_key_bytes),
                       sizeof(master_key_bytes)));
 }
diff --git a/chrome/browser/chromeos/power/peripheral_battery_observer.cc b/chrome/browser/chromeos/power/peripheral_battery_observer.cc
index 1ef701e2..7867495 100644
--- a/chrome/browser/chromeos/power/peripheral_battery_observer.cc
+++ b/chrome/browser/chromeos/power/peripheral_battery_observer.cc
@@ -61,8 +61,8 @@ std::string ExtractBluetoothAddress(const std::string& path) {
   int key_len = path.size() - header_size - end_size;
   if (key_len <= 0)
     return std::string();
-  std::string reverse_address = path.substr(header_size, key_len);
-  base::StringToLowerASCII(&reverse_address);
+  std::string reverse_address =
+      base::ToLowerASCII(path.substr(header_size, key_len));
   std::vector<std::string> result = base::SplitString(
       reverse_address, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
   std::reverse(result.begin(), result.end());
@@ -181,8 +181,7 @@ void PeripheralBatteryObserver::InitializeOnBluetoothReady(
 
 void PeripheralBatteryObserver::RemoveBattery(const std::string& address) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  std::string address_lowercase = address;
-  base::StringToLowerASCII(&address_lowercase);
+  std::string address_lowercase = base::ToLowerASCII(address);
   std::map<std::string, BatteryInfo>::iterator it =
       batteries_.find(address_lowercase);
   if (it != batteries_.end()) {
diff --git a/chrome/browser/chromeos/settings/token_encryptor.cc b/chrome/browser/chromeos/settings/token_encryptor.cc
index 28bc6a7..dbe26c5 100644
--- a/chrome/browser/chromeos/settings/token_encryptor.cc
+++ b/chrome/browser/chromeos/settings/token_encryptor.cc
@@ -88,9 +88,9 @@ std::string CryptohomeTokenEncryptor::EncryptTokenWithKey(
     return std::string();
   }
 
-  return base::StringToLowerASCII(base::HexEncode(
-      reinterpret_cast<const void*>(encoded_token.data()),
-      encoded_token.size()));
+  return base::ToLowerASCII(
+      base::HexEncode(reinterpret_cast<const void*>(encoded_token.data()),
+                      encoded_token.size()));
 }
 
 std::string CryptohomeTokenEncryptor::DecryptTokenWithKey(
diff --git a/chrome/browser/component_updater/supervised_user_whitelist_installer_unittest.cc b/chrome/browser/component_updater/supervised_user_whitelist_installer_unittest.cc
index dad559f..48b0b97 100644
--- a/chrome/browser/component_updater/supervised_user_whitelist_installer_unittest.cc
+++ b/chrome/browser/component_updater/supervised_user_whitelist_installer_unittest.cc
@@ -259,7 +259,7 @@ TEST_F(SupervisedUserWhitelistInstallerTest, GetHashFromCrxId) {
 
   {
     std::string extension_id = "aBcDeFgHiJkLmNoPpOnMlKjIhGfEdCbA";
-    ASSERT_EQ(base::StringToLowerASCII(extension_id),
+    ASSERT_EQ(base::ToLowerASCII(extension_id),
               CrxIdToHashToCrxId(extension_id));
   }
 
diff --git a/chrome/browser/enumerate_modules_model_win.cc b/chrome/browser/enumerate_modules_model_win.cc
index 6786fb3..a940c2e 100644
--- a/chrome/browser/enumerate_modules_model_win.cc
+++ b/chrome/browser/enumerate_modules_model_win.cc
@@ -349,7 +349,7 @@ static void GenerateHash(const std::string& input, std::string* output) {
 
   uint8 hash[4];
   crypto::SHA256HashString(input, hash, sizeof(hash));
-  *output = base::StringToLowerASCII(base::HexEncode(hash, sizeof(hash)));
+  *output = base::ToLowerASCII(base::HexEncode(hash, sizeof(hash)));
 }
 
 // -----------------------------------------------------------------------------
diff --git a/chrome/browser/extensions/api/file_system/file_system_api.cc b/chrome/browser/extensions/api/file_system/file_system_api.cc
index 3f033d4..58e9bfb 100644
--- a/chrome/browser/extensions/api/file_system/file_system_api.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_api.cc
@@ -151,8 +151,7 @@ bool GetFileTypesFromAcceptOption(
     for (std::vector<std::string>::const_iterator iter = list->begin();
          iter != list->end(); ++iter) {
       std::vector<base::FilePath::StringType> inner;
-      std::string accept_type = *iter;
-      base::StringToLowerASCII(&accept_type);
+      std::string accept_type = base::ToLowerASCII(*iter);
       net::GetExtensionsForMimeType(accept_type, &inner);
       if (inner.empty())
         continue;
@@ -176,8 +175,7 @@ bool GetFileTypesFromAcceptOption(
     std::vector<std::string>* list = accept_option.extensions.get();
     for (std::vector<std::string>::const_iterator iter = list->begin();
          iter != list->end(); ++iter) {
-      std::string extension = *iter;
-      base::StringToLowerASCII(&extension);
+      std::string extension = base::ToLowerASCII(*iter);
 #if defined(OS_WIN)
       extension_set.insert(base::UTF8ToWide(*iter));
 #else
diff --git a/chrome/browser/extensions/api/gcm/gcm_api.cc b/chrome/browser/extensions/api/gcm/gcm_api.cc
index ba76151..60dd292 100644
--- a/chrome/browser/extensions/api/gcm/gcm_api.cc
+++ b/chrome/browser/extensions/api/gcm/gcm_api.cc
@@ -67,7 +67,7 @@ const char* GcmResultToError(gcm::GCMClient::Result result) {
 }
 
 bool IsMessageKeyValid(const std::string& key) {
-  std::string lower = base::StringToLowerASCII(key);
+  std::string lower = base::ToLowerASCII(key);
   return !key.empty() &&
          key.compare(0, arraysize(kCollapseKey) - 1, kCollapseKey) != 0 &&
          lower.compare(0,
diff --git a/chrome/browser/extensions/api/music_manager_private/device_id.cc b/chrome/browser/extensions/api/music_manager_private/device_id.cc
index b72b805..b0391ba 100644
--- a/chrome/browser/extensions/api/music_manager_private/device_id.cc
+++ b/chrome/browser/extensions/api/music_manager_private/device_id.cc
@@ -24,7 +24,7 @@ bool ComputeHmacSha256(const std::string& key,
   bool result = hmac.Init(key) &&
       hmac.Sign(text, &digest[0], digest.size());
   if (result) {
-    *signature_return = base::StringToLowerASCII(
+    *signature_return = base::ToLowerASCII(
         base::HexEncode(digest.data(), digest.size()));
   }
   return result;
diff --git a/chrome/browser/extensions/api/music_manager_private/device_id_linux.cc b/chrome/browser/extensions/api/music_manager_private/device_id_linux.cc
index bb65b59..e334706 100644
--- a/chrome/browser/extensions/api/music_manager_private/device_id_linux.cc
+++ b/chrome/browser/extensions/api/music_manager_private/device_id_linux.cc
@@ -124,7 +124,7 @@ class MacAddressProcessor {
 
     // Got one!
     found_mac_address_ =
-        base::StringToLowerASCII(base::HexEncode(mac_address, MAC_LENGTH));
+        base::ToLowerASCII(base::HexEncode(mac_address, MAC_LENGTH));
     return false;
   }
 
diff --git a/chrome/browser/extensions/api/music_manager_private/device_id_mac.cc b/chrome/browser/extensions/api/music_manager_private/device_id_mac.cc
index c6664bf..06a3ba7 100644
--- a/chrome/browser/extensions/api/music_manager_private/device_id_mac.cc
+++ b/chrome/browser/extensions/api/music_manager_private/device_id_mac.cc
@@ -133,7 +133,7 @@ class MacAddressProcessor {
     if (!is_valid_mac_address_.Run(mac_address, mac_address_size))
       return keep_going;
 
-    std::string mac_address_string = base::StringToLowerASCII(base::HexEncode(
+    std::string mac_address_string = base::ToLowerASCII(base::HexEncode(
         mac_address, mac_address_size));
 
     base::ScopedCFTypeRef<CFStringRef> provider_class(
diff --git a/chrome/browser/extensions/api/music_manager_private/device_id_win.cc b/chrome/browser/extensions/api/music_manager_private/device_id_win.cc
index 1ea8b8d..c418624 100644
--- a/chrome/browser/extensions/api/music_manager_private/device_id_win.cc
+++ b/chrome/browser/extensions/api/music_manager_private/device_id_win.cc
@@ -76,7 +76,7 @@ class MacAddressProcessor {
     if (!is_valid_mac_address_.Run(bytes, size))
       return;
 
-    found_mac_address_ = base::StringToLowerASCII(base::HexEncode(bytes, size));
+    found_mac_address_ = base::ToLowerASCII(base::HexEncode(bytes, size));
     found_index_ = index;
   }
 
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 88b0a12..3ed9706 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -2116,7 +2116,7 @@ void ExtensionService::TerminateExtension(const std::string& extension_id) {
 }
 
 void ExtensionService::UntrackTerminatedExtension(const std::string& id) {
-  std::string lowercase_id = base::StringToLowerASCII(id);
+  std::string lowercase_id = base::ToLowerASCII(id);
   const Extension* extension =
       registry_->terminated_extensions().GetByID(lowercase_id);
   registry_->RemoveTerminated(lowercase_id);
diff --git a/chrome/browser/extensions/external_registry_loader_win.cc b/chrome/browser/extensions/external_registry_loader_win.cc
index a1c2893..0b5a67f 100644
--- a/chrome/browser/extensions/external_registry_loader_win.cc
+++ b/chrome/browser/extensions/external_registry_loader_win.cc
@@ -98,8 +98,7 @@ void ExternalRegistryLoader::LoadOnFileThread() {
       continue;
     }
 
-    std::string id = base::UTF16ToASCII(*it);
-    base::StringToLowerASCII(&id);
+    std::string id = base::ToLowerASCII(base::UTF16ToASCII(*it));
     if (!crx_file::id_util::IdIsValid(id)) {
       LOG(ERROR) << "Invalid id value " << id
                  << " for key " << key_path << ".";
diff --git a/chrome/browser/extensions/updater/local_extension_cache.cc b/chrome/browser/extensions/updater/local_extension_cache.cc
index 14273a8..e265b8c 100644
--- a/chrome/browser/extensions/updater/local_extension_cache.cc
+++ b/chrome/browser/extensions/updater/local_extension_cache.cc
@@ -75,7 +75,7 @@ LocalExtensionCache::CacheMap::iterator LocalExtensionCache::FindExtension(
     const std::string& expected_hash) {
   CacheHit hit = cache.equal_range(id);
   CacheMap::iterator empty_hash = cache.end();
-  std::string hash = base::StringToLowerASCII(expected_hash);
+  std::string hash = base::ToLowerASCII(expected_hash);
   for (CacheMap::iterator it = hit.first; it != hit.second; ++it) {
     if (expected_hash.empty() || it->second.expected_hash == hash) {
       return it;
@@ -437,7 +437,7 @@ void LocalExtensionCache::BackendCheckCacheContentsInternal(
     }
 
     // Enforce a lower-case id.
-    id = base::StringToLowerASCII(id);
+    id = base::ToLowerASCII(id);
     if (!crx_file::id_util::IdIsValid(id)) {
       LOG(ERROR) << "Bad extension id in cache: " << id;
       id.clear();
@@ -486,7 +486,7 @@ std::string LocalExtensionCache::ExtensionFileName(
     const std::string& expected_hash) {
   std::string filename = id + "-" + version;
   if (!expected_hash.empty())
-    filename += "-" + base::StringToLowerASCII(expected_hash);
+    filename += "-" + base::ToLowerASCII(expected_hash);
   filename += kCRXFileExtension;
   return filename;
 }
@@ -612,7 +612,7 @@ LocalExtensionCache::CacheItemInfo::CacheItemInfo(
     uint64 size,
     const base::FilePath& file_path)
     : version(version),
-      expected_hash(base::StringToLowerASCII(expected_hash)),
+      expected_hash(base::ToLowerASCII(expected_hash)),
       last_used(last_used),
       size(size),
       file_path(file_path) {
diff --git a/chrome/browser/extensions/updater/local_extension_cache_unittest.cc b/chrome/browser/extensions/updater/local_extension_cache_unittest.cc
index 4113060..3fe8a2b 100644
--- a/chrome/browser/extensions/updater/local_extension_cache_unittest.cc
+++ b/chrome/browser/extensions/updater/local_extension_cache_unittest.cc
@@ -105,7 +105,7 @@ class LocalExtensionCacheTest : public testing::Test {
     uint8 output[crypto::kSHA256Length];
     hash->Finish(output, sizeof(output));
     const std::string hex_hash =
-        base::StringToLowerASCII(base::HexEncode(output, sizeof(output)));
+        base::ToLowerASCII(base::HexEncode(output, sizeof(output)));
     delete hash;
 
     const base::FilePath file =
diff --git a/chrome/browser/file_select_helper.cc b/chrome/browser/file_select_helper.cc
index 6d88afb..bbfae1b 100644
--- a/chrome/browser/file_select_helper.cc
+++ b/chrome/browser/file_select_helper.cc
@@ -565,7 +565,7 @@ bool FileSelectHelper::IsAcceptTypeValid(const std::string& accept_type) {
   // of an extension or a "/" in the case of a MIME type).
   std::string unused;
   if (accept_type.length() <= 1 ||
-      base::StringToLowerASCII(accept_type) != accept_type ||
+      base::ToLowerASCII(accept_type) != accept_type ||
       base::TrimWhitespaceASCII(accept_type, base::TRIM_ALL, &unused) !=
           base::TRIM_NONE) {
     return false;
diff --git a/chrome/browser/icon_loader_chromeos.cc b/chrome/browser/icon_loader_chromeos.cc
index 8a2e378..603b2ff 100644
--- a/chrome/browser/icon_loader_chromeos.cc
+++ b/chrome/browser/icon_loader_chromeos.cc
@@ -183,7 +183,7 @@ int IconSizeToDIPSize(IconLoader::IconSize size) {
 // static
 IconGroupID IconLoader::ReadGroupIDFromFilepath(
     const base::FilePath& filepath) {
-  return base::StringToLowerASCII(filepath.Extension());
+  return base::ToLowerASCII(filepath.Extension());
 }
 
 // static
diff --git a/chrome/browser/importer/in_process_importer_bridge.cc b/chrome/browser/importer/in_process_importer_bridge.cc
index ccf8a33..4098109 100644
--- a/chrome/browser/importer/in_process_importer_bridge.cc
+++ b/chrome/browser/importer/in_process_importer_bridge.cc
@@ -78,7 +78,7 @@ class FirefoxURLParameterFilter : public TemplateURLParser::ParameterFilter {
   // TemplateURLParser::ParameterFilter method.
   bool KeepParameter(const std::string& key,
                      const std::string& value) override {
-    std::string low_value = base::StringToLowerASCII(value);
+    std::string low_value = base::ToLowerASCII(value);
     if (low_value.find("mozilla") != std::string::npos ||
         low_value.find("firefox") != std::string::npos ||
         low_value.find("moz:") != std::string::npos) {
diff --git a/chrome/browser/install_verification/win/module_verification_common.cc b/chrome/browser/install_verification/win/module_verification_common.cc
index 0d28858..e249491 100644
--- a/chrome/browser/install_verification/win/module_verification_common.cc
+++ b/chrome/browser/install_verification/win/module_verification_common.cc
@@ -13,7 +13,7 @@
 #include "chrome/browser/install_verification/win/module_list.h"
 
 std::string CalculateModuleNameDigest(const base::string16& module_name) {
-  return base::MD5String(base::StringToLowerASCII(base::UTF16ToUTF8(
+  return base::MD5String(base::ToLowerASCII(base::UTF16ToUTF8(
       base::FilePath(module_name).BaseName().value())));
 }
 
diff --git a/chrome/browser/media_galleries/fileapi/media_path_filter.cc b/chrome/browser/media_galleries/fileapi/media_path_filter.cc
index 5b27f10..d7d41e6 100644
--- a/chrome/browser/media_galleries/fileapi/media_path_filter.cc
+++ b/chrome/browser/media_galleries/fileapi/media_path_filter.cc
@@ -152,8 +152,7 @@ bool MediaPathFilter::Match(const base::FilePath& path) {
 MediaGalleryScanFileType MediaPathFilter::GetType(const base::FilePath& path) {
   EnsureInitialized();
   MediaFileExtensionMap::const_iterator it =
-      media_file_extensions_map_.find(
-          base::StringToLowerASCII(path.Extension()));
+      media_file_extensions_map_.find(base::ToLowerASCII(path.Extension()));
   if (it == media_file_extensions_map_.end())
     return MEDIA_GALLERY_SCAN_FILE_TYPE_UNKNOWN;
   return static_cast<MediaGalleryScanFileType>(it->second);
diff --git a/chrome/browser/profile_resetter/automatic_profile_resetter_delegate.cc b/chrome/browser/profile_resetter/automatic_profile_resetter_delegate.cc
index b120f7c..b74329f 100644
--- a/chrome/browser/profile_resetter/automatic_profile_resetter_delegate.cc
+++ b/chrome/browser/profile_resetter/automatic_profile_resetter_delegate.cc
@@ -113,7 +113,7 @@ void ExtractLoadedModuleNameDigests(
     std::string module_name;
     if (!module_dictionary->GetString("name", &module_name))
       continue;
-    base::StringToLowerASCII(&module_name);
+    module_name = base::ToLowerASCII(module_name);
     module_name_digests->AppendString(base::MD5String(module_name));
   }
 }
diff --git a/chrome/browser/profiles/profile_io_data.cc b/chrome/browser/profiles/profile_io_data.cc
index 614c0cb..0c9bcdd 100644
--- a/chrome/browser/profiles/profile_io_data.cc
+++ b/chrome/browser/profiles/profile_io_data.cc
@@ -697,7 +697,7 @@ ProfileIOData* ProfileIOData::FromResourceContext(
 
 // static
 bool ProfileIOData::IsHandledProtocol(const std::string& scheme) {
-  DCHECK_EQ(scheme, base::StringToLowerASCII(scheme));
+  DCHECK_EQ(scheme, base::ToLowerASCII(scheme));
   static const char* const kProtocolList[] = {
     url::kFileScheme,
     content::kChromeDevToolsScheme,
diff --git a/chrome/browser/renderer_host/pepper/device_id_fetcher.cc b/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
index b859d22..3ec5777 100644
--- a/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
+++ b/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
@@ -159,13 +159,13 @@ void DeviceIDFetcher::ComputeOnUIThread(const std::string& salt,
   input.append(kDRMIdentifierFile);
   input.append(salt_bytes.begin(), salt_bytes.end());
   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
-  std::string id = base::StringToLowerASCII(
+  std::string id = base::ToLowerASCII(
       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
   input = machine_id;
   input.append(kDRMIdentifierFile);
   input.append(id);
   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
-  id = base::StringToLowerASCII(
+  id = base::ToLowerASCII(
       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
 
   RunCallbackOnIOThread(id, PP_OK);
diff --git a/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win.cc b/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win.cc
index 65ee030..1b64370 100644
--- a/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win.cc
+++ b/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win.cc
@@ -34,7 +34,7 @@ bool GetLoadedBlacklistedModules(std::vector<base::string16>* module_names) {
 
   std::set<ModuleInfo>::const_iterator module_iter(module_info_set.begin());
   for (; module_iter != module_info_set.end(); ++module_iter) {
-    base::string16 module_file_name(base::StringToLowerASCII(
+    base::string16 module_file_name(base::ToLowerASCII(
         base::FilePath(module_iter->name).BaseName().value()));
     if (blacklist::GetBlacklistIndex(module_file_name.c_str()) != -1) {
       module_names->push_back(module_iter->name);
diff --git a/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win_unittest.cc b/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win_unittest.cc
index 6edafbf..b15549e 100644
--- a/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win_unittest.cc
+++ b/chrome/browser/safe_browsing/incident_reporting/blacklist_load_analyzer_win_unittest.cc
@@ -44,7 +44,7 @@ TEST(BlacklistLoadAnalyzer, TestBlacklistBypass) {
   EXPECT_TRUE(GetLoadedBlacklistedModules(&module_names));
   ASSERT_EQ(1, module_names.size());
   EXPECT_STREQ(kTestDllName,
-               base::StringToLowerASCII(
+               base::ToLowerASCII(
                    base::FilePath(module_names[0]).BaseName().value()).c_str());
 }
 
diff --git a/chrome/browser/search/hotword_service.cc b/chrome/browser/search/hotword_service.cc
index 30d12f0..3611432 100644
--- a/chrome/browser/search/hotword_service.cc
+++ b/chrome/browser/search/hotword_service.cc
@@ -268,8 +268,7 @@ class HotwordNotificationDelegate : public NotificationDelegate {
 // static
 bool HotwordService::DoesHotwordSupportLanguage(Profile* profile) {
   std::string normalized_locale =
-      l10n_util::NormalizeLocale(GetCurrentLocale(profile));
-  base::StringToLowerASCII(&normalized_locale);
+      base::ToLowerASCII(l10n_util::NormalizeLocale(GetCurrentLocale(profile)));
 
   // For M43, we are limiting always-on to en_us only.
   // TODO(kcarattini): Remove this once
diff --git a/chrome/browser/shell_integration_win.cc b/chrome/browser/shell_integration_win.cc
index 860c239..a8e4e5c 100644
--- a/chrome/browser/shell_integration_win.cc
+++ b/chrome/browser/shell_integration_win.cc
@@ -386,7 +386,7 @@ bool ShellIntegration::IsFirefoxDefaultBrowser() {
     base::string16 app_cmd;
     if (key.Valid() && (key.ReadValue(L"", &app_cmd) == ERROR_SUCCESS) &&
         base::string16::npos !=
-        base::StringToLowerASCII(app_cmd).find(L"firefox"))
+        base::ToLowerASCII(app_cmd).find(L"firefox"))
       ff_default = true;
   }
   return ff_default;
diff --git a/chrome/browser/spellchecker/spellcheck_hunspell_dictionary.cc b/chrome/browser/spellchecker/spellcheck_hunspell_dictionary.cc
index 9a538d4..5463f40 100644
--- a/chrome/browser/spellchecker/spellcheck_hunspell_dictionary.cc
+++ b/chrome/browser/spellchecker/spellcheck_hunspell_dictionary.cc
@@ -228,7 +228,7 @@ GURL SpellcheckHunspellDictionary::GetDictionaryURL() {
   DCHECK(!bdict_file.empty());
 
   return GURL(std::string(kDownloadServerUrl) +
-              base::StringToLowerASCII(bdict_file));
+              base::ToLowerASCII(bdict_file));
 }
 
 void SpellcheckHunspellDictionary::DownloadDictionary(GURL url) {
diff --git a/chrome/browser/ui/webui/extensions/extension_icon_source.cc b/chrome/browser/ui/webui/extensions/extension_icon_source.cc
index 2b40ccd..a2218eb 100644
--- a/chrome/browser/ui/webui/extensions/extension_icon_source.cc
+++ b/chrome/browser/ui/webui/extensions/extension_icon_source.cc
@@ -277,7 +277,7 @@ bool ExtensionIconSource::ParseData(
     int request_id,
     const content::URLDataSource::GotDataCallback& callback) {
   // Extract the parameters from the path by lower casing and splitting.
-  std::string path_lower = base::StringToLowerASCII(path);
+  std::string path_lower = base::ToLowerASCII(path);
   std::vector<std::string> path_parts = base::SplitString(
       path_lower, "/", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
   if (path_lower.empty() || path_parts.size() < 3)
diff --git a/chrome/common/custom_handlers/protocol_handler.cc b/chrome/common/custom_handlers/protocol_handler.cc
index 8ede72d..75fc274 100644
--- a/chrome/common/custom_handlers/protocol_handler.cc
+++ b/chrome/common/custom_handlers/protocol_handler.cc
@@ -18,7 +18,7 @@ ProtocolHandler::ProtocolHandler(const std::string& protocol,
 ProtocolHandler ProtocolHandler::CreateProtocolHandler(
     const std::string& protocol,
     const GURL& url) {
-  std::string lower_protocol = base::StringToLowerASCII(protocol);
+  std::string lower_protocol = base::ToLowerASCII(protocol);
   return ProtocolHandler(lower_protocol, url);
 }
 
diff --git a/chrome/common/extensions/api/file_browser_handlers/file_browser_handler.cc b/chrome/common/extensions/api/file_browser_handlers/file_browser_handler.cc
index 9ec60f0..f0508a9 100644
--- a/chrome/common/extensions/api/file_browser_handlers/file_browser_handler.cc
+++ b/chrome/common/extensions/api/file_browser_handlers/file_browser_handler.cc
@@ -199,7 +199,7 @@ FileBrowserHandler* LoadFileBrowserHandler(
             errors::kInvalidFileFilterValue, base::IntToString(i));
         return NULL;
       }
-      base::StringToLowerASCII(&filter);
+      filter = base::ToLowerASCII(filter);
       if (!base::StartsWith(filter, std::string(url::kFileSystemScheme) + ':',
                             base::CompareCase::SENSITIVE)) {
         *error = extensions::ErrorUtils::FormatErrorMessageUTF16(
diff --git a/chrome/common/importer/firefox_importer_utils.cc b/chrome/common/importer/firefox_importer_utils.cc
index 3b74d6f..4dfb76e 100644
--- a/chrome/common/importer/firefox_importer_utils.cc
+++ b/chrome/common/importer/firefox_importer_utils.cc
@@ -319,7 +319,7 @@ base::string16 GetFirefoxImporterName(const base::FilePath& app_path) {
     }
   }
 
-  base::StringToLowerASCII(&branding_name);
+  branding_name = base::ToLowerASCII(branding_name);
   if (branding_name.find("iceweasel") != std::string::npos)
     return l10n_util::GetStringUTF16(IDS_IMPORT_FROM_ICEWEASEL);
   return l10n_util::GetStringUTF16(IDS_IMPORT_FROM_FIREFOX);
diff --git a/chrome/installer/util/language_selector.cc b/chrome/installer/util/language_selector.cc
index 1c1a582..aa8555f 100644
--- a/chrome/installer/util/language_selector.cc
+++ b/chrome/installer/util/language_selector.cc
@@ -243,13 +243,9 @@ bool LanguageSelector::SelectIf(const std::vector<std::wstring>& candidates,
                                 SelectPred_Fn select_predicate,
                                 std::wstring* matched_name,
                                 int* matched_offset) {
-  std::wstring candidate;
-  for (std::vector<std::wstring>::const_iterator scan = candidates.begin(),
-          end = candidates.end(); scan != end; ++scan) {
-    candidate.assign(*scan);
-    base::StringToLowerASCII(&candidate);
-    if (select_predicate(candidate, matched_offset)) {
-      matched_name->assign(*scan);
+  for (const std::wstring& scan : candidates) {
+    if (select_predicate(base::ToLowerASCII(scan), matched_offset)) {
+      matched_name->assign(scan);
       return true;
     }
   }
diff --git a/chrome/renderer/pepper/pepper_flash_renderer_host.cc b/chrome/renderer/pepper/pepper_flash_renderer_host.cc
index 63a0533..1fccbff 100644
--- a/chrome/renderer/pepper/pepper_flash_renderer_host.cc
+++ b/chrome/renderer/pepper/pepper_flash_renderer_host.cc
@@ -315,7 +315,7 @@ int32_t PepperFlashRendererHost::OnNavigate(
   bool rejected = false;
   while (header_iter.GetNext()) {
     std::string lower_case_header_name =
-        base::StringToLowerASCII(header_iter.name());
+        base::ToLowerASCII(header_iter.name());
     if (!IsSimpleHeader(lower_case_header_name, header_iter.values())) {
       rejected = true;
 
diff --git a/chrome/renderer/plugins/plugin_uma.cc b/chrome/renderer/plugins/plugin_uma.cc
index 4040f63..9272d3c 100644
--- a/chrome/renderer/plugins/plugin_uma.cc
+++ b/chrome/renderer/plugins/plugin_uma.cc
@@ -106,7 +106,7 @@ void PluginUMAReporter::ExtractFileExtension(const GURL& src,
     extension->clear();
   }
 
-  base::StringToLowerASCII(extension);
+  *extension = base::ToLowerASCII(*extension);
 }
 
 PluginUMAReporter::PluginType PluginUMAReporter::GetPluginType(
@@ -115,7 +115,7 @@ PluginUMAReporter::PluginType PluginUMAReporter::GetPluginType(
   // If we know plugin's mime type, we use it to determine plugin's type. Else,
   // we try to determine plugin type using plugin source's extension.
   if (!plugin_mime_type.empty())
-    return MimeTypeToPluginType(base::StringToLowerASCII(plugin_mime_type));
+    return MimeTypeToPluginType(base::ToLowerASCII(plugin_mime_type));
 
   return SrcToPluginType(plugin_src);
 }
diff --git a/chrome/renderer/safe_browsing/phishing_dom_feature_extractor.cc b/chrome/renderer/safe_browsing/phishing_dom_feature_extractor.cc
index f47a186..d5bda8e 100644
--- a/chrome/renderer/safe_browsing/phishing_dom_feature_extractor.cc
+++ b/chrome/renderer/safe_browsing/phishing_dom_feature_extractor.cc
@@ -327,8 +327,7 @@ void PhishingDOMFeatureExtractor::HandleInput(
   // Note that we use the attribute value rather than
   // WebFormControlElement::formControlType() for consistency with the
   // way the phishing classification model is created.
-  std::string type = element.getAttribute("type").utf8();
-  base::StringToLowerASCII(&type);
+  std::string type = base::ToLowerASCII(element.getAttribute("type").utf8());
   if (type == "password") {
     ++page_feature_state_->num_pswd_inputs;
   } else if (type == "radio") {
diff --git a/chrome/test/chromedriver/capabilities.cc b/chrome/test/chromedriver/capabilities.cc
index bc5bbbb..e4ba863 100644
--- a/chrome/test/chromedriver/capabilities.cc
+++ b/chrome/test/chromedriver/capabilities.cc
@@ -211,7 +211,7 @@ Status ParseProxy(const base::Value& option, Capabilities* capabilities) {
   std::string proxy_type;
   if (!proxy_dict->GetString("proxyType", &proxy_type))
     return Status(kUnknownError, "'proxyType' must be a string");
-  proxy_type = base::StringToLowerASCII(proxy_type);
+  proxy_type = base::ToLowerASCII(proxy_type);
   if (proxy_type == "direct") {
     capabilities->switches.SetSwitch("no-proxy-server");
   } else if (proxy_type == "system") {
diff --git a/chrome/test/chromedriver/chrome_launcher.cc b/chrome/test/chromedriver/chrome_launcher.cc
index cb77dc1..90ddede 100644
--- a/chrome/test/chromedriver/chrome_launcher.cc
+++ b/chrome/test/chromedriver/chrome_launcher.cc
@@ -573,8 +573,7 @@ void ConvertHexadecimalToIDAlphabet(std::string* id) {
 std::string GenerateExtensionId(const std::string& input) {
   uint8 hash[16];
   crypto::SHA256HashString(input, hash, sizeof(hash));
-  std::string output =
-      base::StringToLowerASCII(base::HexEncode(hash, sizeof(hash)));
+  std::string output = base::ToLowerASCII(base::HexEncode(hash, sizeof(hash)));
   ConvertHexadecimalToIDAlphabet(&output);
   return output;
 }
diff --git a/chrome/test/chromedriver/server/http_handler.cc b/chrome/test/chromedriver/server/http_handler.cc
index 63c0a95..c3941b0 100644
--- a/chrome/test/chromedriver/server/http_handler.cc
+++ b/chrome/test/chromedriver/server/http_handler.cc
@@ -722,14 +722,14 @@ namespace internal {
 const char kNewSessionPathPattern[] = "session";
 
 bool MatchesMethod(HttpMethod command_method, const std::string& method) {
-  std::string lower_method = base::StringToLowerASCII(method);
+  std::string lower_method = base::ToLowerASCII(method);
   switch (command_method) {
-  case kGet:
-    return lower_method == "get";
-  case kPost:
-    return lower_method == "post" || lower_method == "put";
-  case kDelete:
-    return lower_method == "delete";
+    case kGet:
+      return lower_method == "get";
+    case kPost:
+      return lower_method == "post" || lower_method == "put";
+    case kDelete:
+      return lower_method == "delete";
   }
   return false;
 }
diff --git a/chromeos/cryptohome/system_salt_getter.cc b/chromeos/cryptohome/system_salt_getter.cc
index 9c2e244..b0bbc9e 100644
--- a/chromeos/cryptohome/system_salt_getter.cc
+++ b/chromeos/cryptohome/system_salt_getter.cc
@@ -95,8 +95,8 @@ SystemSaltGetter* SystemSaltGetter::Get() {
 // static
 std::string SystemSaltGetter::ConvertRawSaltToHexString(
     const std::vector<uint8>& salt) {
-  return base::StringToLowerASCII(base::HexEncode(
-      reinterpret_cast<const void*>(salt.data()), salt.size()));
+  return base::ToLowerASCII(
+      base::HexEncode(reinterpret_cast<const void*>(salt.data()), salt.size()));
 }
 
 }  // namespace chromeos
diff --git a/chromeos/login/auth/key.cc b/chromeos/login/auth/key.cc
index 01c3bcf..fe3ec86 100644
--- a/chromeos/login/auth/key.cc
+++ b/chromeos/login/auth/key.cc
@@ -84,7 +84,7 @@ void Key::Transform(KeyType target_key_type, const std::string& salt) {
       // Keep only the first half of the hash for 'weak' hashing so that the
       // plain text secret cannot be reconstructed even if the hashing is
       // reversed.
-      secret_ = base::StringToLowerASCII(base::HexEncode(
+      secret_ = base::ToLowerASCII(base::HexEncode(
           reinterpret_cast<const void*>(hash), sizeof(hash) / 2));
       break;
     }
diff --git a/cloud_print/gcp20/prototype/print_job_handler.cc b/cloud_print/gcp20/prototype/print_job_handler.cc
index 557aa2e..d76114b 100644
--- a/cloud_print/gcp20/prototype/print_job_handler.cc
+++ b/cloud_print/gcp20/prototype/print_job_handler.cc
@@ -35,7 +35,7 @@ bool ValidateTicket(const std::string& ticket) {
 }
 
 std::string GenerateId() {
-  return base::StringToLowerASCII(base::GenerateGUID());
+  return base::ToLowerASCII(base::GenerateGUID());
 }
 
 }  // namespace
diff --git a/components/audio_modem/modem_impl.cc b/components/audio_modem/modem_impl.cc
index 23d75d0..480204d 100644
--- a/components/audio_modem/modem_impl.cc
+++ b/components/audio_modem/modem_impl.cc
@@ -62,7 +62,7 @@ std::string AudioTypeToString(AudioType audio_type) {
 }
 
 bool ReadBooleanFlag(const std::string& flag, bool default_value) {
-  const std::string flag_value = base::StringToLowerASCII(
+  const std::string flag_value = base::ToLowerASCII(
       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(flag));
   if (flag_value == "true" || flag_value == "1")
     return true;
diff --git a/components/autofill/content/browser/wallet/required_action.cc b/components/autofill/content/browser/wallet/required_action.cc
index 9516f50..444d91f 100644
--- a/components/autofill/content/browser/wallet/required_action.cc
+++ b/components/autofill/content/browser/wallet/required_action.cc
@@ -35,7 +35,7 @@ bool ActionAppliesToWalletItems(RequiredAction action) {
 
 RequiredAction ParseRequiredActionFromString(const std::string& str) {
   std::string str_lower;
-  base::TrimWhitespaceASCII(base::StringToLowerASCII(str), base::TRIM_ALL,
+  base::TrimWhitespaceASCII(base::ToLowerASCII(str), base::TRIM_ALL,
                             &str_lower);
 
   if (str_lower == "setup_wallet")
diff --git a/components/autofill/core/browser/form_structure.cc b/components/autofill/core/browser/form_structure.cc
index 526848f..1b97561 100644
--- a/components/autofill/core/browser/form_structure.cc
+++ b/components/autofill/core/browser/form_structure.cc
@@ -1105,7 +1105,7 @@ void FormStructure::ParseFieldTypesFromAutocompleteAttributes(
     // non-space characters (e.g. tab) to spaces, and converting to lowercase.
     std::string autocomplete_attribute =
         base::CollapseWhitespaceASCII(field->autocomplete_attribute, false);
-    autocomplete_attribute = base::StringToLowerASCII(autocomplete_attribute);
+    autocomplete_attribute = base::ToLowerASCII(autocomplete_attribute);
 
     // The autocomplete attribute is overloaded: it can specify either a field
     // type hint or whether autocomplete should be enabled at all.  Ignore the
diff --git a/components/autofill/core/browser/personal_data_manager.cc b/components/autofill/core/browser/personal_data_manager.cc
index 2e643a8..870b1f6 100644
--- a/components/autofill/core/browser/personal_data_manager.cc
+++ b/components/autofill/core/browser/personal_data_manager.cc
@@ -1061,23 +1061,22 @@ bool PersonalDataManager::IsCountryOfInterest(const std::string& country_code)
   const std::vector<AutofillProfile*>& profiles = web_profiles();
   std::list<std::string> country_codes;
   for (size_t i = 0; i < profiles.size(); ++i) {
-    country_codes.push_back(base::StringToLowerASCII(base::UTF16ToASCII(
+    country_codes.push_back(base::ToLowerASCII(base::UTF16ToASCII(
         profiles[i]->GetRawInfo(ADDRESS_HOME_COUNTRY))));
   }
 
   std::string timezone_country = CountryCodeForCurrentTimezone();
   if (!timezone_country.empty())
-    country_codes.push_back(base::StringToLowerASCII(timezone_country));
+    country_codes.push_back(base::ToLowerASCII(timezone_country));
 
   // Only take the locale into consideration if all else fails.
   if (country_codes.empty()) {
-    country_codes.push_back(base::StringToLowerASCII(
+    country_codes.push_back(base::ToLowerASCII(
         AutofillCountry::CountryCodeForLocale(app_locale())));
   }
 
   return std::find(country_codes.begin(), country_codes.end(),
-                   base::StringToLowerASCII(country_code)) !=
-                       country_codes.end();
+                   base::ToLowerASCII(country_code)) != country_codes.end();
 }
 
 const std::string& PersonalDataManager::GetDefaultCountryCodeForNewAddress()
diff --git a/components/autofill/core/common/save_password_progress_logger.cc b/components/autofill/core/common/save_password_progress_logger.cc
index cfa3a58..456289b 100644
--- a/components/autofill/core/common/save_password_progress_logger.cc
+++ b/components/autofill/core/common/save_password_progress_logger.cc
@@ -43,7 +43,7 @@ bool IsUnwantedInElementID(char c) {
 std::string ScrubElementID8Bit(std::string element_id) {
   std::replace_if(
       element_id.begin(), element_id.end(), IsUnwantedInElementID, ' ');
-  return base::StringToLowerASCII(element_id);
+  return base::ToLowerASCII(element_id);
 }
 
 SavePasswordProgressLogger::StringID FormSchemeToStringID(
diff --git a/components/content_settings/core/common/content_settings_pattern.cc b/components/content_settings/core/common/content_settings_pattern.cc
index 634e487..1b49ba6 100644
--- a/components/content_settings/core/common/content_settings_pattern.cc
+++ b/components/content_settings/core/common/content_settings_pattern.cc
@@ -211,7 +211,7 @@ ContentSettingsPattern ContentSettingsPattern::Builder::Build() {
 // static
 bool ContentSettingsPattern::Builder::Canonicalize(PatternParts* parts) {
   // Canonicalize the scheme part.
-  const std::string scheme(base::StringToLowerASCII(parts->scheme));
+  const std::string scheme(base::ToLowerASCII(parts->scheme));
   parts->scheme = scheme;
 
   if (parts->scheme == std::string(url::kFileScheme) &&
diff --git a/components/crx_file/crx_file.cc b/components/crx_file/crx_file.cc
index b081fec..ace6ee1 100644
--- a/components/crx_file/crx_file.cc
+++ b/components/crx_file/crx_file.cc
@@ -61,7 +61,7 @@ CrxFile::ValidateError FinalizeHash(const std::string& extension_id,
   uint8 output[crypto::kSHA256Length] = {};
   hash->Finish(output, sizeof(output));
   std::string hash_base64 =
-      base::StringToLowerASCII(base::HexEncode(output, sizeof(output)));
+      base::ToLowerASCII(base::HexEncode(output, sizeof(output)));
   if (hash_base64 != expected_hash) {
     LOG(ERROR) << "Hash check failed for extension: " << extension_id
                << ", expected " << expected_hash << ", got " << hash_base64;
diff --git a/components/crx_file/id_util.cc b/components/crx_file/id_util.cc
index 6209cb4..d628aa1 100644
--- a/components/crx_file/id_util.cc
+++ b/components/crx_file/id_util.cc
@@ -40,7 +40,7 @@ std::string GenerateId(const std::string& input) {
   uint8 hash[kIdSize];
   crypto::SHA256HashString(input, hash, sizeof(hash));
   std::string output =
-      base::StringToLowerASCII(base::HexEncode(hash, sizeof(hash)));
+      base::ToLowerASCII(base::HexEncode(hash, sizeof(hash)));
   ConvertHexadecimalToIDAlphabet(&output);
 
   return output;
@@ -83,7 +83,7 @@ bool IdIsValid(const std::string& id) {
 
   // We only support lowercase IDs, because IDs can be used as URL components
   // (where GURL will lowercase it).
-  std::string temp = base::StringToLowerASCII(id);
+  std::string temp = base::ToLowerASCII(id);
   for (size_t i = 0; i < temp.size(); i++)
     if (temp[i] < 'a' || temp[i] > 'p')
       return false;
diff --git a/components/device_event_log/device_event_log_impl.cc b/components/device_event_log/device_event_log_impl.cc
index 7b339b5..94ee5fd 100644
--- a/components/device_event_log/device_event_log_impl.cc
+++ b/components/device_event_log/device_event_log_impl.cc
@@ -220,7 +220,7 @@ void GetFormat(const std::string& format_string,
 }
 
 LogType LogTypeFromString(const std::string& desc) {
-  std::string desc_lc = base::StringToLowerASCII(desc);
+  std::string desc_lc = base::ToLowerASCII(desc);
   if (desc_lc == "network")
     return LOG_TYPE_NETWORK;
   if (desc_lc == "power")
diff --git a/components/history/core/browser/url_utils.cc b/components/history/core/browser/url_utils.cc
index 54dc5a9..522af9b 100644
--- a/components/history/core/browser/url_utils.cc
+++ b/components/history/core/browser/url_utils.cc
@@ -88,7 +88,6 @@ GURL ToggleHTTPAndHTTPS(const GURL& url) {
 
 std::string HostForTopHosts(const GURL& url) {
   std::string host = url.host();
-  base::StringToLowerASCII(&host);
   if (base::StartsWith(host, "www.", base::CompareCase::SENSITIVE))
     host.assign(host, 4, std::string::npos);
   return host;
diff --git a/components/language_usage_metrics/language_usage_metrics.cc b/components/language_usage_metrics/language_usage_metrics.cc
index 190507f..ac44499 100644
--- a/components/language_usage_metrics/language_usage_metrics.cc
+++ b/components/language_usage_metrics/language_usage_metrics.cc
@@ -42,8 +42,7 @@ int LanguageUsageMetrics::ToLanguageCode(const std::string& locale) {
   if (!parts.GetNext())
     return 0;
 
-  std::string language_part = parts.token();
-  base::StringToLowerASCII(&language_part);
+  std::string language_part = base::ToLowerASCII(parts.token());
 
   int language_code = 0;
   for (std::string::iterator it = language_part.begin();
diff --git a/components/mime_util/mime_util.cc b/components/mime_util/mime_util.cc
index 49bf49d..6c51a9e 100644
--- a/components/mime_util/mime_util.cc
+++ b/components/mime_util/mime_util.cc
@@ -151,8 +151,7 @@ MimeUtil::MimeUtil() {
 }
 
 bool MimeUtil::IsSupportedImageMimeType(const std::string& mime_type) const {
-  return image_types_.find(base::StringToLowerASCII(mime_type)) !=
-         image_types_.end();
+  return image_types_.find(base::ToLowerASCII(mime_type)) != image_types_.end();
 }
 
 bool MimeUtil::IsSupportedNonImageMimeType(const std::string& mime_type) const {
diff --git a/components/nacl/renderer/nexe_load_manager.cc b/components/nacl/renderer/nexe_load_manager.cc
index b7c9968..2494820 100644
--- a/components/nacl/renderer/nexe_load_manager.cc
+++ b/components/nacl/renderer/nexe_load_manager.cc
@@ -343,7 +343,7 @@ void NexeLoadManager::InitializePlugin(
   }
 
   // Store mime_type_ at initialization time since we make it lowercase.
-  mime_type_ = base::StringToLowerASCII(LookupAttribute(args_, kTypeAttribute));
+  mime_type_ = base::ToLowerASCII(LookupAttribute(args_, kTypeAttribute));
 }
 
 void NexeLoadManager::ReportStartupOverhead() const {
diff --git a/components/nacl/renderer/ppb_nacl_private_impl.cc b/components/nacl/renderer/ppb_nacl_private_impl.cc
index d9edcb2..dde4ef8 100644
--- a/components/nacl/renderer/ppb_nacl_private_impl.cc
+++ b/components/nacl/renderer/ppb_nacl_private_impl.cc
@@ -1559,7 +1559,7 @@ class PexeDownloader : public blink::WebURLLoaderClient {
 
     for (const std::string& cur : base::SplitString(
              cache_control, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) {
-      if (base::StringToLowerASCII(cur) == "no-store")
+      if (base::ToLowerASCII(cur) == "no-store")
         has_no_store_header = true;
     }
 
diff --git a/components/os_crypt/ie7_password_win.cc b/components/os_crypt/ie7_password_win.cc
index a2691f9..eebd57b 100644
--- a/components/os_crypt/ie7_password_win.cc
+++ b/components/os_crypt/ie7_password_win.cc
@@ -95,7 +95,7 @@ bool GetUserPassFromData(const std::vector<unsigned char>& data,
 }
 
 std::wstring GetUrlHash(const std::wstring& url) {
-  std::wstring lower_case_url = base::StringToLowerASCII(url);
+  std::wstring lower_case_url = base::ToLowerASCII(url);
   // Get a data buffer out of our std::wstring to pass to SHA1HashString.
   std::string url_buffer(
       reinterpret_cast<const char*>(lower_case_url.c_str()),
@@ -121,7 +121,7 @@ std::wstring GetUrlHash(const std::wstring& url) {
 bool DecryptPasswords(const std::wstring& url,
                       const std::vector<unsigned char>& data,
                       std::vector<DecryptedCredentials>* credentials) {
-  std::wstring lower_case_url = base::StringToLowerASCII(url);
+  std::wstring lower_case_url = base::ToLowerASCII(url);
   DATA_BLOB input = {0};
   DATA_BLOB output = {0};
   DATA_BLOB url_key = {0};
diff --git a/components/plugins/renderer/mobile_youtube_plugin.cc b/components/plugins/renderer/mobile_youtube_plugin.cc
index 7b576df..563ec26 100644
--- a/components/plugins/renderer/mobile_youtube_plugin.cc
+++ b/components/plugins/renderer/mobile_youtube_plugin.cc
@@ -49,15 +49,16 @@ bool IsValidYouTubeVideo(const std::string& path) {
   if (path.length() <= len)
     return false;
 
-  std::string str = base::StringToLowerASCII(path);
   // Youtube flash url can start with /v/ or /e/.
-  if (strncmp(str.data(), kSlashVSlash, len) != 0 &&
-      strncmp(str.data(), kSlashESlash, len) != 0)
+  if (!base::StartsWith(path, kSlashVSlash,
+                        base::CompareCase::INSENSITIVE_ASCII) ||
+      !base::StartsWith(path, kSlashESlash,
+                        base::CompareCase::INSENSITIVE_ASCII))
     return false;
 
   // Start after /v/
   for (unsigned i = len; i < path.length(); i++) {
-    char c = str[i];
+    char c = path[i];
     if (isalpha(c) || isdigit(c) || c == '_' || c == '-')
       continue;
     // The url can have more parameters such as &hl=en after the video id.
diff --git a/components/policy/core/common/preg_parser_win.cc b/components/policy/core/common/preg_parser_win.cc
index 08e4fa2..abdf371 100644
--- a/components/policy/core/common/preg_parser_win.cc
+++ b/components/policy/core/common/preg_parser_win.cc
@@ -186,7 +186,7 @@ void HandleRecord(const base::string16& key_name,
     return;
   }
 
-  std::string action_trigger(base::StringToLowerASCII(value_name.substr(
+  std::string action_trigger(base::ToLowerASCII(value_name.substr(
       arraysize(kActionTriggerPrefix) - 1)));
   if (action_trigger == kActionTriggerDeleteValues) {
     for (const std::string& value :
diff --git a/components/query_parser/snippet_unittest.cc b/components/query_parser/snippet_unittest.cc
index c560d58..727734a 100644
--- a/components/query_parser/snippet_unittest.cc
+++ b/components/query_parser/snippet_unittest.cc
@@ -96,7 +96,7 @@ base::string16 BuildSnippet(const std::string& document,
   // |document|. We need to add more test cases and change this function
   // to be more generic depending on how we deal with 'folding for match'
   // in history.
-  const std::string document_folded = base::StringToLowerASCII(document);
+  const std::string document_folded = base::ToLowerASCII(document);
 
   // Manually construct match_positions of the document.
   Snippet::MatchPositions match_positions;
diff --git a/components/signin/core/browser/signin_internals_util.cc b/components/signin/core/browser/signin_internals_util.cc
index 5eb9e5b..fa9d492 100644
--- a/components/signin/core/browser/signin_internals_util.cc
+++ b/components/signin/core/browser/signin_internals_util.cc
@@ -68,7 +68,7 @@ std::string GetTruncatedHash(const std::string& str) {
   const int kTruncateSize = kTruncateTokenStringLength / 2;
   char hash_val[kTruncateSize];
   crypto::SHA256HashString(str, &hash_val[0], kTruncateSize);
-  return base::StringToLowerASCII(base::HexEncode(&hash_val[0], kTruncateSize));
+  return base::ToLowerASCII(base::HexEncode(&hash_val[0], kTruncateSize));
 }
 
 } //  namespace signin_internals_util
diff --git a/components/storage_monitor/media_storage_util.cc b/components/storage_monitor/media_storage_util.cc
index 45dbdf7..13cbdce 100644
--- a/components/storage_monitor/media_storage_util.cc
+++ b/components/storage_monitor/media_storage_util.cc
@@ -99,7 +99,7 @@ bool MediaStorageUtil::HasDcim(const base::FilePath& mount_point) {
   if (!base::DirectoryExists(mount_point.Append(dcim_dir))) {
     // Check for lowercase 'dcim' as well.
     base::FilePath dcim_path_lower(
-        mount_point.Append(base::StringToLowerASCII(dcim_dir)));
+        mount_point.Append(base::ToLowerASCII(dcim_dir)));
     if (!base::DirectoryExists(dcim_path_lower))
       return false;
   }
diff --git a/components/user_prefs/tracked/pref_hash_calculator.cc b/components/user_prefs/tracked/pref_hash_calculator.cc
index 6034262..3d5b7fa 100644
--- a/components/user_prefs/tracked/pref_hash_calculator.cc
+++ b/components/user_prefs/tracked/pref_hash_calculator.cc
@@ -85,7 +85,7 @@ std::string GenerateDeviceIdLikePrefMetricsServiceDid(
     const std::string& original_device_id) {
   if (original_device_id.empty())
     return std::string();
-  return base::StringToLowerASCII(
+  return base::ToLowerASCII(
       GetDigestString(original_device_id, "PrefMetricsService"));
 }