Move JoinString to the base namespace.

Change "Separator" from string to StringPIece (most are constants). Remove char versions for symmetry with SplitString.

Update callers who pass empty separators to use a base::StringPiece()

Change chromecast/base/metrics/cast_metrics_helper.cc to not use JoinString at all and just append to the output (code is simpler and faster).

TBR=zelidrag@chromium.org for chromeos

Review URL: https://codereview.chromium.org/1223153003

Cr-Commit-Position: refs/heads/master@{#338762}

138 files changed, 259 insertions, 254 deletions

diff --git a/android_webview/native/aw_web_contents_delegate.cc b/android_webview/native/aw_web_contents_delegate.cc
index bc7e026..1d22633 100644
--- a/android_webview/native/aw_web_contents_delegate.cc
+++ b/android_webview/native/aw_web_contents_delegate.cc
@@ -16,6 +16,7 @@
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
@@ -114,7 +115,7 @@ void AwWebContentsDelegate::RunFileChooser(WebContents* web_contents,
       web_contents->GetRenderViewHost()->GetRoutingID(),
       mode_flags,
       ConvertUTF16ToJavaString(env,
-        JoinString(params.accept_types, ',')).obj(),
+          base::JoinString(params.accept_types, base::ASCIIToUTF16(","))).obj(),
       params.title.empty() ? NULL :
           ConvertUTF16ToJavaString(env, params.title).obj(),
       params.default_file_name.empty() ? NULL :
@@ -293,7 +294,7 @@ static void FilesSelectedInChooser(
     mode = FileChooserParams::Open;
   }
   DVLOG(0) << "File Chooser result: mode = " << mode
-           << ", file paths = " << JoinString(file_path_str, ":");
+           << ", file paths = " << base::JoinString(file_path_str, ":");
   rvh->FilesSelectedInChooser(files, mode);
 }
 
diff --git a/ash/system/chromeos/tray_display.cc b/ash/system/chromeos/tray_display.cc
index 9419b77..20040ec 100644
--- a/ash/system/chromeos/tray_display.cc
+++ b/ash/system/chromeos/tray_display.cc
@@ -108,7 +108,7 @@ base::string16 GetAllDisplayInfo() {
     lines.push_back(GetDisplayInfoLine(id));
   }
 
-  return JoinString(lines, '\n');
+  return base::JoinString(lines, base::ASCIIToUTF16("\n"));
 }
 
 void OpenSettings() {
diff --git a/ash/system/chromeos/tray_display_unittest.cc b/ash/system/chromeos/tray_display_unittest.cc
index bef870e..f6c205f 100644
--- a/ash/system/chromeos/tray_display_unittest.cc
+++ b/ash/system/chromeos/tray_display_unittest.cc
@@ -46,7 +46,7 @@ base::string16 GetTooltipText(const base::string16& headline,
         IDS_ASH_STATUS_TRAY_DISPLAY_SINGLE_DISPLAY,
         name2, base::UTF8ToUTF16(data2)));
   }
-  return JoinString(lines, '\n');
+  return base::JoinString(lines, base::ASCIIToUTF16("\n"));
 }
 
 base::string16 GetMirroredTooltipText(const base::string16& headline,
diff --git a/ash/system/user/button_from_view.cc b/ash/system/user/button_from_view.cc
index c48401c..b3c434d 100644
--- a/ash/system/user/button_from_view.cc
+++ b/ash/system/user/button_from_view.cc
@@ -89,7 +89,7 @@ void ButtonFromView::GetAccessibleState(ui::AXViewState* state) {
   std::vector<base::string16> labels;
   for (int i = 0; i < child_count(); ++i)
     GetAccessibleLabelFromDescendantViews(child_at(i), labels);
-  state->name = JoinString(labels, base::ASCIIToUTF16(" "));
+  state->name = base::JoinString(labels, base::ASCIIToUTF16(" "));
 }
 
 void ButtonFromView::ShowActive() {
diff --git a/ash/system/user/user_card_view.cc b/ash/system/user/user_card_view.cc
index 3844251..5201688 100644
--- a/ash/system/user/user_card_view.cc
+++ b/ash/system/user/user_card_view.cc
@@ -355,7 +355,7 @@ void UserCardView::GetAccessibleState(ui::AXViewState* state) {
   std::vector<base::string16> labels;
   for (int i = 0; i < child_count(); ++i)
     GetAccessibleLabelFromDescendantViews(child_at(i), labels);
-  state->name = JoinString(labels, base::ASCIIToUTF16(" "));
+  state->name = base::JoinString(labels, base::ASCIIToUTF16(" "));
 }
 
 void UserCardView::AddPublicModeUserContent(int max_width) {
diff --git a/base/debug/crash_logging.cc b/base/debug/crash_logging.cc
index f9b4449..058b476 100644
--- a/base/debug/crash_logging.cc
+++ b/base/debug/crash_logging.cc
@@ -119,7 +119,7 @@ void SetCrashKeyFromAddresses(const base::StringPiece& key,
       hex_backtrace.push_back(s);
     }
 
-    value = JoinString(hex_backtrace, ' ');
+    value = base::JoinString(hex_backtrace, " ");
 
     // Warn if this exceeds the breakpad limits.
     DCHECK_LE(value.length(), kBreakpadValueMax);
diff --git a/base/strings/string_util.cc b/base/strings/string_util.cc
index ae5fb80..a0c95ec 100644
--- a/base/strings/string_util.cc
+++ b/base/strings/string_util.cc
@@ -884,43 +884,36 @@ char16* WriteInto(base::string16* str, size_t length_with_null) {
   return WriteIntoT(str, length_with_null);
 }
 
-}  // namespace base
-
 template<typename STR>
-static STR JoinStringT(const std::vector<STR>& parts, const STR& sep) {
+static STR JoinStringT(const std::vector<STR>& parts,
+                       BasicStringPiece<STR> sep) {
   if (parts.empty())
     return STR();
 
   STR result(parts[0]);
-  typename std::vector<STR>::const_iterator iter = parts.begin();
+  auto iter = parts.begin();
   ++iter;
 
   for (; iter != parts.end(); ++iter) {
-    result += sep;
+    sep.AppendToString(&result);
     result += *iter;
   }
 
   return result;
 }
 
-std::string JoinString(const std::vector<std::string>& parts, char sep) {
-  return JoinStringT(parts, std::string(1, sep));
-}
-
-string16 JoinString(const std::vector<string16>& parts, char16 sep) {
-  return JoinStringT(parts, string16(1, sep));
-}
-
 std::string JoinString(const std::vector<std::string>& parts,
-                       const std::string& separator) {
+                       StringPiece separator) {
   return JoinStringT(parts, separator);
 }
 
 string16 JoinString(const std::vector<string16>& parts,
-                    const string16& separator) {
+                    StringPiece16 separator) {
   return JoinStringT(parts, separator);
 }
 
+}  // namespace base
+
 template<class FormatStringType, class OutStringType>
 OutStringType DoReplaceStringPlaceholders(const FormatStringType& format_string,
     const std::vector<OutStringType>& subst, std::vector<size_t>* offsets) {
diff --git a/base/strings/string_util.h b/base/strings/string_util.h
index e4abce2..b75a9f88 100644
--- a/base/strings/string_util.h
+++ b/base/strings/string_util.h
@@ -491,6 +491,12 @@ BASE_EXPORT char16* WriteInto(base::string16* str, size_t length_with_null);
 BASE_EXPORT wchar_t* WriteInto(std::wstring* str, size_t length_with_null);
 #endif
 
+// Does the opposite of SplitString().
+BASE_EXPORT std::string JoinString(const std::vector<std::string>& parts,
+                                   StringPiece separator);
+BASE_EXPORT string16 JoinString(const std::vector<string16>& parts,
+                                StringPiece16 separator);
+
 }  // namespace base
 
 #if defined(OS_WIN)
@@ -501,22 +507,6 @@ BASE_EXPORT wchar_t* WriteInto(std::wstring* str, size_t length_with_null);
 #error Define string operations appropriately for your platform
 #endif
 
-//-----------------------------------------------------------------------------
-
-// Does the opposite of SplitString().
-BASE_EXPORT base::string16 JoinString(const std::vector<base::string16>& parts,
-                                      base::char16 s);
-BASE_EXPORT std::string JoinString(
-    const std::vector<std::string>& parts, char s);
-
-// Join |parts| using |separator|.
-BASE_EXPORT std::string JoinString(
-    const std::vector<std::string>& parts,
-    const std::string& separator);
-BASE_EXPORT base::string16 JoinString(
-    const std::vector<base::string16>& parts,
-    const base::string16& separator);
-
 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively.
 // Additionally, any number of consecutive '$' characters is replaced by that
 // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be
diff --git a/base/strings/string_util_unittest.cc b/base/strings/string_util_unittest.cc
index 1593f81..5d5ba8b 100644
--- a/base/strings/string_util_unittest.cc
+++ b/base/strings/string_util_unittest.cc
@@ -669,26 +669,7 @@ TEST(StringUtilTest, HexDigitToInt) {
   EXPECT_EQ(15, HexDigitToInt('f'));
 }
 
-// Test for JoinString
 TEST(StringUtilTest, JoinString) {
-  std::vector<std::string> in;
-  EXPECT_EQ("", JoinString(in, ','));
-
-  in.push_back("a");
-  EXPECT_EQ("a", JoinString(in, ','));
-
-  in.push_back("b");
-  in.push_back("c");
-  EXPECT_EQ("a,b,c", JoinString(in, ','));
-
-  in.push_back(std::string());
-  EXPECT_EQ("a,b,c,", JoinString(in, ','));
-  in.push_back(" ");
-  EXPECT_EQ("a|b|c|| ", JoinString(in, '|'));
-}
-
-// Test for JoinString overloaded with std::string separator
-TEST(StringUtilTest, JoinStringWithString) {
   std::string separator(", ");
   std::vector<std::string> parts;
   EXPECT_EQ(std::string(), JoinString(parts, separator));
@@ -706,8 +687,7 @@ TEST(StringUtilTest, JoinStringWithString) {
   EXPECT_EQ("a|b|c|| ", JoinString(parts, "|"));
 }
 
-// Test for JoinString overloaded with string16 separator
-TEST(StringUtilTest, JoinStringWithString16) {
+TEST(StringUtilTest, JoinString16) {
   string16 separator = ASCIIToUTF16(", ");
   std::vector<string16> parts;
   EXPECT_EQ(string16(), JoinString(parts, separator));
diff --git a/base/test/launcher/test_launcher.cc b/base/test/launcher/test_launcher.cc
index 2a56b6c..7c0bc4e 100644
--- a/base/test/launcher/test_launcher.cc
+++ b/base/test/launcher/test_launcher.cc
@@ -570,7 +570,7 @@ void TestLauncher::OnTestFinished(const TestResult& result) {
           snippet_lines.begin() + truncated_size);
       snippet_lines.insert(snippet_lines.begin(), "<truncated>");
     }
-    fprintf(stdout, "%s", JoinString(snippet_lines, "\n").c_str());
+    fprintf(stdout, "%s", base::JoinString(snippet_lines, "\n").c_str());
     fflush(stdout);
   }
 
diff --git a/base/test/launcher/test_launcher_ios.cc b/base/test/launcher/test_launcher_ios.cc
index ecd31ae..3179bb3 100644
--- a/base/test/launcher/test_launcher_ios.cc
+++ b/base/test/launcher/test_launcher_ios.cc
@@ -121,7 +121,7 @@ class IOSUnitTestPlatformDelegate : public base::UnitTestPlatformDelegate {
     base::CommandLine cmd_line(dir_exe_.AppendASCII(test_name_ + ".app"));
     cmd_line.AppendSwitchPath(switches::kTestLauncherOutput, output_file);
     cmd_line.AppendSwitchASCII(base::kGTestFilterFlag,
-                               JoinString(test_names, ":"));
+                               base::JoinString(test_names, ":"));
     return cmd_line;
   }
 
diff --git a/base/test/launcher/test_launcher_nacl_nonsfi.cc b/base/test/launcher/test_launcher_nacl_nonsfi.cc
index fa52604..bf117af 100644
--- a/base/test/launcher/test_launcher_nacl_nonsfi.cc
+++ b/base/test/launcher/test_launcher_nacl_nonsfi.cc
@@ -113,7 +113,7 @@ class NonSfiUnitTestPlatformDelegate : public base::UnitTestPlatformDelegate {
     cmd_line.AppendSwitchPath(
         switches::kTestLauncherOutput, output_file);
     cmd_line.AppendSwitchASCII(
-        base::kGTestFilterFlag, JoinString(test_names, ":"));
+        base::kGTestFilterFlag, base::JoinString(test_names, ":"));
     return cmd_line;
   }
 
diff --git a/base/trace_event/trace_event_impl.cc b/base/trace_event/trace_event_impl.cc
index f01a888..cd8cf4a 100644
--- a/base/trace_event/trace_event_impl.cc
+++ b/base/trace_event/trace_event_impl.cc
@@ -2352,7 +2352,7 @@ void TraceLog::AddMetadataEventsWhileLocked() {
     InitializeMetadataEvent(AddEventToThreadSharedChunkWhileLocked(NULL, false),
                             current_thread_id,
                             "process_labels", "labels",
-                            JoinString(labels, ','));
+                            base::JoinString(labels, ","));
   }
 
   // Thread sort indices.
diff --git a/chrome/browser/android/preferences/pref_service_bridge.cc b/chrome/browser/android/preferences/pref_service_bridge.cc
index 5b13882..1d85d79 100644
--- a/chrome/browser/android/preferences/pref_service_bridge.cc
+++ b/chrome/browser/android/preferences/pref_service_bridge.cc
@@ -835,7 +835,7 @@ void PrefServiceBridge::PrependToAcceptLanguagesIfNecessary(
       parts.push_back(language);
     }
     parts.push_back(*accept_languages);
-    *accept_languages = JoinString(parts, ',');
+    *accept_languages = base::JoinString(parts, ",");
   }
 }
 
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index e00b5e1..163c614 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -1231,7 +1231,7 @@ void MaybeAppendBlinkSettingsSwitchForFieldTrial(
   }
 
   command_line->AppendSwitchASCII(switches::kBlinkSettings,
-                                  JoinString(blink_settings, ','));
+                                  base::JoinString(blink_settings, ","));
 }
 
 }  // namespace
diff --git a/chrome/browser/chromeos/accessibility/accessibility_manager.cc b/chrome/browser/chromeos/accessibility/accessibility_manager.cc
index 279bf3b..993d426 100644
--- a/chrome/browser/chromeos/accessibility/accessibility_manager.cc
+++ b/chrome/browser/chromeos/accessibility/accessibility_manager.cc
@@ -845,7 +845,7 @@ void AccessibilityManager::UpdateBrailleImeState() {
   else
     preload_engines.erase(it);
   pref_service->SetString(prefs::kLanguagePreloadEngines,
-                          JoinString(preload_engines, ','));
+                          base::JoinString(preload_engines, ","));
   braille_ime_current_ = false;
 }
 
diff --git a/chrome/browser/chromeos/input_method/input_method_manager_impl.cc b/chrome/browser/chromeos/input_method/input_method_manager_impl.cc
index bff428c..89a42bb 100644
--- a/chrome/browser/chromeos/input_method/input_method_manager_impl.cc
+++ b/chrome/browser/chromeos/input_method/input_method_manager_impl.cc
@@ -610,7 +610,8 @@ void InputMethodManagerImpl::StateImpl::SetInputMethodLoginDefaultFromVPD(
   manager_->MigrateInputMethods(&layouts);
 
   PrefService* prefs = g_browser_process->local_state();
-  prefs->SetString(prefs::kHardwareKeyboardLayout, JoinString(layouts, ","));
+  prefs->SetString(prefs::kHardwareKeyboardLayout,
+                   base::JoinString(layouts, ","));
 
   // This asks the file thread to save the prefs (i.e. doesn't block).
   // The latest values of Local State reside in memory so we can safely
diff --git a/chrome/browser/chromeos/input_method/input_method_syncer.cc b/chrome/browser/chromeos/input_method/input_method_syncer.cc
index b76080c..6823f23 100644
--- a/chrome/browser/chromeos/input_method/input_method_syncer.cc
+++ b/chrome/browser/chromeos/input_method/input_method_syncer.cc
@@ -92,7 +92,7 @@ std::string CheckAndResolveLocales(const std::string& languages) {
     value_iter = values.erase(value_iter);
   }
 
-  return JoinString(values, ',');
+  return base::JoinString(values, ",");
 }
 
 // Appends tokens from |src| that are not in |dest| to |dest|.
@@ -197,14 +197,14 @@ void InputMethodSyncer::MergeSyncedPrefs() {
 
   // Append the synced values to the current values.
   MergeLists(&new_tokens, synced_tokens);
-  preferred_languages_syncable_.SetValue(JoinString(new_tokens, ','));
+  preferred_languages_syncable_.SetValue(base::JoinString(new_tokens, ","));
 
   base::SplitString(
       enabled_extension_imes_syncable_.GetValue(), ',', &synced_tokens);
   base::SplitString(enabled_extension_imes_.GetValue(), ',', &new_tokens);
 
   MergeLists(&new_tokens, synced_tokens);
-  enabled_extension_imes_syncable_.SetValue(JoinString(new_tokens, ','));
+  enabled_extension_imes_syncable_.SetValue(base::JoinString(new_tokens, ","));
 
   // Revert preload engines to legacy component IDs.
   base::SplitString(preload_engines_.GetValue(), ',', &new_tokens);
@@ -214,7 +214,7 @@ void InputMethodSyncer::MergeSyncedPrefs() {
       preload_engines_syncable_.GetValue(), ',', &synced_tokens);
 
   MergeLists(&new_tokens, synced_tokens);
-  preload_engines_syncable_.SetValue(JoinString(new_tokens, ','));
+  preload_engines_syncable_.SetValue(base::JoinString(new_tokens, ","));
 
   // Second, set the local prefs, incorporating new values from the sync server.
   preload_engines_.SetValue(
@@ -278,7 +278,7 @@ std::string InputMethodSyncer::AddSupportedInputMethodValues(
 
   // Do the actual merging.
   MergeLists(&old_tokens, new_tokens);
-  return JoinString(old_tokens, ',');
+  return base::JoinString(old_tokens, ",");
 }
 
 void InputMethodSyncer::FinishMerge(const std::string& languages) {
@@ -311,7 +311,7 @@ void InputMethodSyncer::OnPreferenceChanged(const std::string& pref_name) {
   base::SplitString(preload_engines_.GetValue(), ',', &engines);
   std::transform(engines.begin(), engines.end(), engines.begin(),
                  extension_ime_util::GetComponentIDByInputMethodID);
-  preload_engines_syncable_.SetValue(JoinString(engines, ','));
+  preload_engines_syncable_.SetValue(base::JoinString(engines, ","));
 }
 
 void InputMethodSyncer::OnIsSyncingChanged() {
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index af0f026..0a02b53 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -156,7 +156,7 @@ void InitLocaleAndInputMethodsForNewUser(
   // Save the input methods in the user's preferences.
   StringPrefMember language_preload_engines;
   language_preload_engines.Init(prefs::kLanguagePreloadEngines, prefs);
-  language_preload_engines.SetValue(JoinString(input_method_ids, ','));
+  language_preload_engines.SetValue(base::JoinString(input_method_ids, ","));
   BootTimesRecorder::Get()->AddLoginTimeMarker("IMEStarted", false);
 
   // Second, we'll set kLanguagePreferredLanguages.
@@ -184,7 +184,7 @@ void InitLocaleAndInputMethodsForNewUser(
 
   // Save the preferred languages in the user's preferences.
   prefs->SetString(prefs::kLanguagePreferredLanguages,
-                   JoinString(language_codes, ','));
+                   base::JoinString(language_codes, ","));
 
   // Indicate that we need to merge the syncable input methods when we sync,
   // since we have not applied the synced prefs before.
diff --git a/chrome/browser/chromeos/power/peripheral_battery_observer.cc b/chrome/browser/chromeos/power/peripheral_battery_observer.cc
index 32438ae2..22089fa 100644
--- a/chrome/browser/chromeos/power/peripheral_battery_observer.cc
+++ b/chrome/browser/chromeos/power/peripheral_battery_observer.cc
@@ -66,7 +66,7 @@ std::string ExtractBluetoothAddress(const std::string& path) {
   std::vector<std::string> result;
   base::SplitString(reverse_address, ':', &result);
   std::reverse(result.begin(), result.end());
-  std::string address = JoinString(result, ':');
+  std::string address = base::JoinString(result, ":");
   return address;
 }
 
diff --git a/chrome/browser/chromeos/preferences.cc b/chrome/browser/chromeos/preferences.cc
index db334bf..e19c8ff 100644
--- a/chrome/browser/chromeos/preferences.cc
+++ b/chrome/browser/chromeos/preferences.cc
@@ -627,7 +627,7 @@ void Preferences::SetLanguageConfigStringListAsCSV(const char* section,
 
   // Transfers the xkb id to extension-xkb id.
   if (input_method_manager_->MigrateInputMethods(&split_values))
-    preload_engines_.SetValue(JoinString(split_values, ','));
+    preload_engines_.SetValue(base::JoinString(split_values, ","));
 
   if (section == std::string(language_prefs::kGeneralSectionName) &&
       name == std::string(language_prefs::kPreloadEnginesConfigName)) {
diff --git a/chrome/browser/chromeos/preferences_unittest.cc b/chrome/browser/chromeos/preferences_unittest.cc
index 60a4829..f790cba 100644
--- a/chrome/browser/chromeos/preferences_unittest.cc
+++ b/chrome/browser/chromeos/preferences_unittest.cc
@@ -344,7 +344,7 @@ class InputMethodPreferencesTest : public PreferencesTest {
     base::SplitString(value, ',', &tokens);
     std::transform(tokens.begin(), tokens.end(), tokens.begin(),
                    &extension_ime_util::GetInputMethodIDByEngineID);
-    return JoinString(tokens, ',');
+    return base::JoinString(tokens, ",");
   }
 
   StringPrefMember preferred_languages_;
diff --git a/chrome/browser/chromeos/system_logs/debug_daemon_log_source.cc b/chrome/browser/chromeos/system_logs/debug_daemon_log_source.cc
index 263d03cb..44e4820 100644
--- a/chrome/browser/chromeos/system_logs/debug_daemon_log_source.cc
+++ b/chrome/browser/chromeos/system_logs/debug_daemon_log_source.cc
@@ -80,7 +80,7 @@ void DebugDaemonLogSource::OnGetRoutes(bool succeeded,
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   if (succeeded)
-    (*response_)[kRoutesKeyName] = JoinString(routes, '\n');
+    (*response_)[kRoutesKeyName] = base::JoinString(routes, "\n");
   else
     (*response_)[kRoutesKeyName] = kNotAvailable;
   RequestCompleted();
diff --git a/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc b/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
index 6b7232e..d97fca42 100644
--- a/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
+++ b/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
@@ -55,7 +55,7 @@ GaiaWebAuthFlow::GaiaWebAuthFlow(Delegate* delegate,
   std::vector<std::string> client_id_parts;
   base::SplitString(oauth2_client_id, '.', &client_id_parts);
   std::reverse(client_id_parts.begin(), client_id_parts.end());
-  redirect_scheme_ = JoinString(client_id_parts, '.');
+  redirect_scheme_ = base::JoinString(client_id_parts, ".");
   std::string signin_scoped_device_id;
   // profile_ can be nullptr in unittests.
   SigninClient* signin_client =
@@ -69,7 +69,7 @@ GaiaWebAuthFlow::GaiaWebAuthFlow(Delegate* delegate,
   std::string oauth2_authorize_params = base::StringPrintf(
       kOAuth2AuthorizeFormat,
       oauth2_client_id.c_str(),
-      net::EscapeUrlEncodedData(JoinString(scopes, ' '), true).c_str(),
+      net::EscapeUrlEncodedData(base::JoinString(scopes, " "), true).c_str(),
       token_key->extension_id.c_str(),
       redirect_scheme_.c_str(),
       token_key->extension_id.c_str(),
diff --git a/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc b/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
index 9110b02..2385a3e 100644
--- a/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
+++ b/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
@@ -168,7 +168,7 @@ CryptoVerifyImpl::Credentials::Credentials(
   data_parts.push_back(properties.device_bssid);
   data_parts.push_back(properties.public_key);
   data_parts.push_back(properties.nonce);
-  unsigned_data = JoinString(data_parts, ",");
+  unsigned_data = base::JoinString(data_parts, ",");
 
   device_bssid = properties.device_bssid;
   public_key = properties.public_key;
diff --git a/chrome/browser/extensions/chrome_content_verifier_delegate.cc b/chrome/browser/extensions/chrome_content_verifier_delegate.cc
index 5e412e7..c181e5e 100644
--- a/chrome/browser/extensions/chrome_content_verifier_delegate.cc
+++ b/chrome/browser/extensions/chrome_content_verifier_delegate.cc
@@ -135,7 +135,7 @@ GURL ChromeContentVerifierDelegate::GetSignatureFetchUrl(
   parts.push_back("id=" + extension_id);
   parts.push_back("v=" + version.GetString());
   std::string x_value =
-      net::EscapeQueryParamValue(JoinString(parts, "&"), true);
+      net::EscapeQueryParamValue(base::JoinString(parts, "&"), true);
   std::string query = "response=redirect&x=" + x_value;
 
   GURL base_url = extension_urls::GetWebstoreUpdateUrl();
diff --git a/chrome/browser/extensions/content_capabilities_browsertest.cc b/chrome/browser/extensions/content_capabilities_browsertest.cc
index 8a4b96b..cb7a512 100644
--- a/chrome/browser/extensions/content_capabilities_browsertest.cc
+++ b/chrome/browser/extensions/content_capabilities_browsertest.cc
@@ -74,7 +74,7 @@ class ContentCapabilitiesTest : public ExtensionApiTest {
       v.push_back(s1);
     if (!s2.empty())
       v.push_back(s2);
-    std::string list = JoinString(v, "\",\"");
+    std::string list = base::JoinString(v, "\",\"");
     if (!list.empty())
       list = "\"" + list + "\"";
     return "[" + list + "]";
diff --git a/chrome/browser/extensions/crx_installer.cc b/chrome/browser/extensions/crx_installer.cc
index 714906c..2effb1a 100644
--- a/chrome/browser/extensions/crx_installer.cc
+++ b/chrome/browser/extensions/crx_installer.cc
@@ -536,8 +536,8 @@ void CrxInstaller::OnInstallChecksComplete(int failed_checks) {
     if (error_on_unsupported_requirements_) {
       ReportFailureFromUIThread(
           CrxInstallError(CrxInstallError::ERROR_DECLINED,
-                          base::UTF8ToUTF16(JoinString(
-                              install_checker_.requirement_errors(), ' '))));
+                          base::UTF8ToUTF16(base::JoinString(
+                              install_checker_.requirement_errors(), " "))));
       return;
     }
     install_flags_ |= kInstallFlagHasRequirementErrors;
diff --git a/chrome/browser/extensions/extension_install_prompt.cc b/chrome/browser/extensions/extension_install_prompt.cc
index 6c093e1..4cdcf4d 100644
--- a/chrome/browser/extensions/extension_install_prompt.cc
+++ b/chrome/browser/extensions/extension_install_prompt.cc
@@ -269,7 +269,8 @@ void ExtensionInstallPrompt::Prompt::SetPermissions(
                                             detail_line);
       }
 
-      details = JoinString(detail_lines_with_bullets, '\n');
+      details = base::JoinString(detail_lines_with_bullets,
+                                 base::ASCIIToUTF16("\n"));
     }
     install_permissions.details.push_back(details);
     install_permissions.is_showing_details.push_back(false);
diff --git a/chrome/browser/extensions/extension_message_bubble_controller.cc b/chrome/browser/extensions/extension_message_bubble_controller.cc
index ac198fd..0bc2802 100644
--- a/chrome/browser/extensions/extension_message_bubble_controller.cc
+++ b/chrome/browser/extensions/extension_message_bubble_controller.cc
@@ -141,7 +141,7 @@ base::string16 ExtensionMessageBubbleController::GetExtensionListForDisplay() {
   base::string16 prefix = bullet_point + base::ASCIIToUTF16(" ");
   for (base::string16& str : extension_list)
     str.insert(0, prefix);
-  return JoinString(extension_list, base::ASCIIToUTF16("\n"));
+  return base::JoinString(extension_list, base::ASCIIToUTF16("\n"));
 }
 
 const ExtensionIdList& ExtensionMessageBubbleController::GetExtensionIdList() {
diff --git a/chrome/browser/extensions/extension_service_unittest.cc b/chrome/browser/extensions/extension_service_unittest.cc
index 0a4c7fa..3378d72 100644
--- a/chrome/browser/extensions/extension_service_unittest.cc
+++ b/chrome/browser/extensions/extension_service_unittest.cc
@@ -1806,8 +1806,9 @@ TEST_F(ExtensionServiceTest, InstallUserScript) {
   EXPECT_TRUE(installed_) << "Nothing was installed.";
   EXPECT_FALSE(was_update_) << path.value();
   ASSERT_EQ(1u, loaded_.size()) << "Nothing was loaded.";
-  EXPECT_EQ(0u, errors.size()) << "There were errors: "
-                               << JoinString(errors, ',');
+  EXPECT_EQ(0u, errors.size())
+      << "There were errors: "
+      << base::JoinString(errors, base::ASCIIToUTF16(","));
   EXPECT_TRUE(service()->GetExtensionById(loaded_[0]->id(), false))
       << path.value();
 
diff --git a/chrome/browser/extensions/extension_startup_browsertest.cc b/chrome/browser/extensions/extension_startup_browsertest.cc
index bf8faf4..ad5f1ab 100644
--- a/chrome/browser/extensions/extension_startup_browsertest.cc
+++ b/chrome/browser/extensions/extension_startup_browsertest.cc
@@ -67,7 +67,9 @@ class ExtensionStartupTestBase : public InProcessBrowserTest {
       unauthenticated_load_allowed_ = false;
 #endif
     } else {
-      base::FilePath::StringType paths = JoinString(load_extensions_, ',');
+      base::FilePath::StringType paths =
+          base::JoinString(load_extensions_,
+                           base::FilePath::StringType(1, ','));
       command_line->AppendSwitchNative(switches::kLoadExtension,
                                        paths);
       command_line->AppendSwitch(switches::kDisableExtensionsFileAccessCheck);
diff --git a/chrome/browser/extensions/requirements_checker_browsertest.cc b/chrome/browser/extensions/requirements_checker_browsertest.cc
index efda739..7ff03d9 100644
--- a/chrome/browser/extensions/requirements_checker_browsertest.cc
+++ b/chrome/browser/extensions/requirements_checker_browsertest.cc
@@ -65,7 +65,7 @@ class RequirementsCheckerBrowserTest : public ExtensionBrowserTest {
       "  \"entries\": [\n"
       "    {\n"
       "      \"id\": 1,\n"
-      "      \"features\": [\"" + JoinString(features, "\", \"") + "\"]\n"
+      "      \"features\": [\"" + base::JoinString(features, "\", \"") + "\"]\n"
       "    }\n"
       "  ]\n"
       "}";
diff --git a/chrome/browser/extensions/unpacked_installer.cc b/chrome/browser/extensions/unpacked_installer.cc
index 5f702b9b..6fd2f9b 100644
--- a/chrome/browser/extensions/unpacked_installer.cc
+++ b/chrome/browser/extensions/unpacked_installer.cc
@@ -251,7 +251,7 @@ void UnpackedInstaller::OnInstallChecksComplete(int failed_checks) {
 
   if (!install_checker_.requirement_errors().empty()) {
     ReportExtensionLoadError(
-        JoinString(install_checker_.requirement_errors(), ' '));
+        base::JoinString(install_checker_.requirement_errors(), " "));
     return;
   }
 
diff --git a/chrome/browser/extensions/webstore_installer.cc b/chrome/browser/extensions/webstore_installer.cc
index cbfd025a..6ab5475 100644
--- a/chrome/browser/extensions/webstore_installer.cc
+++ b/chrome/browser/extensions/webstore_installer.cc
@@ -217,7 +217,8 @@ GURL WebstoreInstaller::GetWebstoreInstallURL(
   GURL url(url_string + "?response=redirect&" +
            update_client::UpdateQueryParams::Get(
                update_client::UpdateQueryParams::CRX) +
-           "&x=" + net::EscapeQueryParamValue(JoinString(params, '&'), true));
+           "&x=" + net::EscapeQueryParamValue(base::JoinString(params, "&"),
+                                              true));
   DCHECK(url.is_valid());
 
   return url;
diff --git a/chrome/browser/net/firefox_proxy_settings.cc b/chrome/browser/net/firefox_proxy_settings.cc
index 2b23e01..203d9557 100644
--- a/chrome/browser/net/firefox_proxy_settings.cc
+++ b/chrome/browser/net/firefox_proxy_settings.cc
@@ -236,7 +236,7 @@ bool FirefoxProxySettings::ToProxyConfig(net::ProxyConfig* config) {
   }
 
   config->proxy_rules().bypass_rules.ParseFromStringUsingSuffixMatching(
-      JoinString(proxy_bypass_list_, ';'));
+      base::JoinString(proxy_bypass_list_, ";"));
 
   return true;
 }
diff --git a/chrome/browser/net/predictor.cc b/chrome/browser/net/predictor.cc
index 9299b63..0241aa0 100644
--- a/chrome/browser/net/predictor.cc
+++ b/chrome/browser/net/predictor.cc
@@ -504,7 +504,7 @@ struct RightToLeftStringSorter {
     std::vector<std::string> parts;
     base::SplitString(url.host(), '.', &parts);
     std::reverse(parts.begin(), parts.end());
-    std::string reversed_host = JoinString(parts, '.');
+    std::string reversed_host = base::JoinString(parts, ".");
 
     // Return the new URL.
     GURL::Replacements url_components;
diff --git a/chrome/browser/net/safe_search_util.cc b/chrome/browser/net/safe_search_util.cc
index 9e34a64..ac29b6f 100644
--- a/chrome/browser/net/safe_search_util.cc
+++ b/chrome/browser/net/safe_search_util.cc
@@ -63,7 +63,7 @@ std::string AddSafeSearchParameters(const std::string& query) {
 
   new_parameters.push_back(safe_parameter);
   new_parameters.push_back(ssui_parameter);
-  return JoinString(new_parameters, '&');
+  return base::JoinString(new_parameters, "&");
 }
 
 } // namespace
diff --git a/chrome/browser/search/suggestions/suggestions_source.cc b/chrome/browser/search/suggestions/suggestions_source.cc
index 486d53d..79ea0be 100644
--- a/chrome/browser/search/suggestions/suggestions_source.cc
+++ b/chrome/browser/search/suggestions/suggestions_source.cc
@@ -78,7 +78,7 @@ void RenderOutputHtml(const SuggestionsProfile& profile,
   }
   out.push_back("</ul>");
   out.push_back(kHtmlFooter);
-  *output = JoinString(out, "");
+  *output = base::JoinString(out, base::StringPiece());
 }
 
 // Fills |output| with the HTML needed to display that no suggestions are
@@ -90,7 +90,7 @@ void RenderOutputHtmlNoSuggestions(std::string* output) {
   out.push_back("<h1>Suggestions</h1>\n");
   out.push_back("<p>You have no suggestions.</p>\n");
   out.push_back(kHtmlFooter);
-  *output = JoinString(out, "");
+  *output = base::JoinString(out, base::StringPiece());
 }
 
 }  // namespace
diff --git a/chrome/browser/ssl/certificate_error_report.cc b/chrome/browser/ssl/certificate_error_report.cc
index 67e8edd..c63e897 100644
--- a/chrome/browser/ssl/certificate_error_report.cc
+++ b/chrome/browser/ssl/certificate_error_report.cc
@@ -56,7 +56,7 @@ bool CertificateChainToString(scoped_refptr<net::X509Certificate> cert,
   if (!cert->GetPEMEncodedChain(&pem_encoded_chain))
     return false;
 
-  *result = JoinString(pem_encoded_chain, std::string());
+  *result = base::JoinString(pem_encoded_chain, base::StringPiece());
   return true;
 }
 
diff --git a/chrome/browser/ssl/ssl_blocking_page.cc b/chrome/browser/ssl/ssl_blocking_page.cc
index b47aa2e..327fbad 100644
--- a/chrome/browser/ssl/ssl_blocking_page.cc
+++ b/chrome/browser/ssl/ssl_blocking_page.cc
@@ -455,7 +455,7 @@ void SSLBlockingPage::PopulateInterstitialStrings(
   ssl_info_.cert->GetPEMEncodedChain(
       &encoded_chain);
   load_time_data->SetString(
-      "pem", JoinString(encoded_chain, std::string()));
+      "pem", base::JoinString(encoded_chain, base::StringPiece()));
 
   cert_report_helper_->PopulateExtendedReportingOption(load_time_data);
 }
diff --git a/chrome/browser/sxs_linux.cc b/chrome/browser/sxs_linux.cc
index 040011d..2990693 100644
--- a/chrome/browser/sxs_linux.cc
+++ b/chrome/browser/sxs_linux.cc
@@ -81,7 +81,7 @@ bool DoAddChannelMarkToUserDataDir(const base::FilePath& user_data_dir) {
   user_data_dir_channels.push_back(product_channel_name);
   return base::ImportantFileWriter::WriteFileAtomically(
       channels_path,
-      JoinString(user_data_dir_channels, "\n"));
+      base::JoinString(user_data_dir_channels, "\n"));
 }
 
 }  // namespace
diff --git a/chrome/browser/sync/profile_sync_service_android_unittest.cc b/chrome/browser/sync/profile_sync_service_android_unittest.cc
index 14c6d0b..0377f12 100644
--- a/chrome/browser/sync/profile_sync_service_android_unittest.cc
+++ b/chrome/browser/sync/profile_sync_service_android_unittest.cc
@@ -97,7 +97,7 @@ TEST_F(ProfileSyncServiceAndroidTest, ModelTypesToInvalidationNames) {
   }
 
   std::sort(invalidation_names.begin(), invalidation_names.end());
-  EXPECT_EQ(JoinString(invalidation_names, ", "),
+  EXPECT_EQ(base::JoinString(invalidation_names, ", "),
             ProfileSyncServiceAndroid::ModelTypeSelectionToStringForTest(
                 model_type_selection));
 }
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
index f120fe3..0859ba1 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
@@ -1743,7 +1743,7 @@ scoped_ptr<base::ListValue> MetadataDatabase::DumpMetadata() {
       std::vector<std::string> parents;
       for (int i = 0; i < details.parent_folder_ids_size(); ++i)
         parents.push_back(details.parent_folder_ids(i));
-      dict->SetString("parents", JoinString(parents, ","));
+      dict->SetString("parents", base::JoinString(parents, ","));
     }
     files->Append(dict);
   }
diff --git a/chrome/browser/thumbnails/thumbnail_list_source.cc b/chrome/browser/thumbnails/thumbnail_list_source.cc
index 604b3d3..0cad21f 100644
--- a/chrome/browser/thumbnails/thumbnail_list_source.cc
+++ b/chrome/browser/thumbnails/thumbnail_list_source.cc
@@ -164,6 +164,6 @@ void ThumbnailListSource::OnMostVisitedURLsAvailable(
   }
   out.push_back(kHtmlFooter);
 
-  std::string out_html = JoinString(out, "");
+  std::string out_html = base::JoinString(out, base::StringPiece());
   callback.Run(base::RefCountedString::TakeString(&out_html));
 }
diff --git a/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc b/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc
index ad9e51f..b664989 100644
--- a/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc
+++ b/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc
@@ -316,7 +316,7 @@ MultiUserWindowManagerChromeOSTest::GetOwnersOfVisibleWindowsAsString() {
 
   std::vector<std::string> owner_list;
   owner_list.insert(owner_list.begin(), owners.begin(), owners.end());
-  return JoinString(owner_list, ' ');
+  return base::JoinString(owner_list, " ");
 }
 
 // Testing basic assumptions like default state and existence of manager.
diff --git a/chrome/browser/ui/autofill/autofill_dialog_types.cc b/chrome/browser/ui/autofill/autofill_dialog_types.cc
index 95dfd44..b990097 100644
--- a/chrome/browser/ui/autofill/autofill_dialog_types.cc
+++ b/chrome/browser/ui/autofill/autofill_dialog_types.cc
@@ -34,7 +34,7 @@ DialogNotification::DialogNotification(Type type,
     size_t start = pieces[0].size();
     size_t end = start + pieces[1].size();
     link_range_ = gfx::Range(start, end);
-    display_text_ = JoinString(pieces, base::string16());
+    display_text_ = base::JoinString(pieces, base::StringPiece16());
   }
 }
 
diff --git a/chrome/browser/ui/autofill/data_model_wrapper.cc b/chrome/browser/ui/autofill/data_model_wrapper.cc
index 2bc42aa..8391286 100644
--- a/chrome/browser/ui/autofill/data_model_wrapper.cc
+++ b/chrome/browser/ui/autofill/data_model_wrapper.cc
@@ -79,7 +79,7 @@ bool DataModelWrapper::GetDisplayText(
   non_address_info += base::ASCIIToUTF16("\n") + phone;
 
   *vertically_compact = base::UTF8ToUTF16(single_line) + non_address_info;
-  *horizontally_compact = base::UTF8ToUTF16(JoinString(lines, "\n")) +
+  *horizontally_compact = base::UTF8ToUTF16(base::JoinString(lines, "\n")) +
       non_address_info;
 
   return true;
diff --git a/chrome/browser/ui/cocoa/global_error_bubble_controller.mm b/chrome/browser/ui/cocoa/global_error_bubble_controller.mm
index c2604d9..d62343f 100644
--- a/chrome/browser/ui/cocoa/global_error_bubble_controller.mm
+++ b/chrome/browser/ui/cocoa/global_error_bubble_controller.mm
@@ -82,7 +82,7 @@ class Bridge : public GlobalErrorBubbleViewBase {
 
   [title_ setStringValue:SysUTF16ToNSString(error_->GetBubbleViewTitle())];
   std::vector<base::string16> messages = error_->GetBubbleViewMessages();
-  base::string16 message = JoinString(messages, '\n');
+  base::string16 message = base::JoinString(messages, base::ASCIIToUTF16("\n"));
 
   base::scoped_nsobject<NSMutableAttributedString> messageValue(
       [[NSMutableAttributedString alloc]
diff --git a/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc b/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
index f9c8b53..638407e 100644
--- a/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
+++ b/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
@@ -319,7 +319,8 @@ void SelectFileDialogImplGTK::AddFilters(GtkFileChooser* chooser) {
       // the extensions themselves if the description is blank.
       std::vector<std::string> fallback_labels_vector(fallback_labels.begin(),
                                                       fallback_labels.end());
-      std::string fallback_label = JoinString(fallback_labels_vector, ',');
+      std::string fallback_label =
+          base::JoinString(fallback_labels_vector, ",");
       gtk_file_filter_set_name(filter, fallback_label.c_str());
     }
 
diff --git a/chrome/browser/ui/webui/gcm_internals_ui.cc b/chrome/browser/ui/webui/gcm_internals_ui.cc
index f5754ce..5fe3189 100644
--- a/chrome/browser/ui/webui/gcm_internals_ui.cc
+++ b/chrome/browser/ui/webui/gcm_internals_ui.cc
@@ -162,7 +162,7 @@ void GcmInternalsUIMessageHandler::ReturnResults(
     device_info->SetBoolean("connectionClientCreated",
                             stats->connection_client_created);
     device_info->SetString("registeredAppIds",
-                           JoinString(stats->registered_app_ids, ","));
+                           base::JoinString(stats->registered_app_ids, ","));
     if (stats->connection_client_created)
       device_info->SetString("connectionState", stats->connection_state);
     if (stats->android_id > 0) {
diff --git a/chrome/common/chrome_content_client.cc b/chrome/common/chrome_content_client.cc
index 6dfb690..60551e7 100644
--- a/chrome/common/chrome_content_client.cc
+++ b/chrome/common/chrome_content_client.cc
@@ -190,8 +190,8 @@ void ComputeBuiltInPlugins(std::vector<content::PepperPluginInfo>* plugins) {
       codecs.push_back(kCdmSupportedCodecAac);
       codecs.push_back(kCdmSupportedCodecAvc1);
 #endif  // defined(USE_PROPRIETARY_CODECS)
-      std::string codec_string =
-          JoinString(codecs, kCdmSupportedCodecsValueDelimiter);
+      std::string codec_string = base::JoinString(
+          codecs, base::string16(1, kCdmSupportedCodecsValueDelimiter));
       widevine_cdm_mime_type.additional_param_names.push_back(
           base::ASCIIToUTF16(kCdmSupportedCodecsParamName));
       widevine_cdm_mime_type.additional_param_values.push_back(
@@ -255,7 +255,7 @@ content::PepperPluginInfo CreatePepperFlashInfo(const base::FilePath& path,
   // E.g., "Shockwave Flash 10.2 r154":
   plugin.description = plugin.name + " " + flash_version_numbers[0] + "." +
       flash_version_numbers[1] + " r" + flash_version_numbers[2];
-  plugin.version = JoinString(flash_version_numbers, '.');
+  plugin.version = base::JoinString(flash_version_numbers, ".");
   content::WebPluginMimeType swf_mime_type(content::kFlashPluginSwfMimeType,
                                            content::kFlashPluginSwfExtension,
                                            content::kFlashPluginSwfDescription);
diff --git a/chrome/common/extensions/command.cc b/chrome/common/extensions/command.cc
index ba42e1c..fc4b47bc 100644
--- a/chrome/common/extensions/command.cc
+++ b/chrome/common/extensions/command.cc
@@ -272,7 +272,7 @@ std::string NormalizeShortcutSuggestion(const std::string& suggestion,
     else if (tokens[i] == values::kKeyMacCtrl)
       tokens[i] = values::kKeyCtrl;
   }
-  return JoinString(tokens, '+');
+  return base::JoinString(tokens, "+");
 }
 
 }  // namespace
diff --git a/chrome/common/extensions/permissions/chrome_permission_message_rules.cc b/chrome/common/extensions/permissions/chrome_permission_message_rules.cc
index 7b68bfa..1083cff2 100644
--- a/chrome/common/extensions/permissions/chrome_permission_message_rules.cc
+++ b/chrome/common/extensions/permissions/chrome_permission_message_rules.cc
@@ -6,6 +6,7 @@
 
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #include "chrome/grit/generated_resources.h"
 #include "extensions/common/permissions/api_permission_set.h"
 #include "extensions/common/permissions/coalesced_permission_message.h"
@@ -98,8 +99,8 @@ class SpaceSeparatedListFormatter : public ChromePermissionMessageFormatter {
     DCHECK(permissions.size() > 0);
     std::vector<base::string16> hostnames =
         permissions.GetAllPermissionParameters();
-    base::string16 hosts_string = JoinString(
-        std::vector<base::string16>(hostnames.begin(), hostnames.end()), ' ');
+    base::string16 hosts_string =
+        base::JoinString(hostnames, base::ASCIIToUTF16(" "));
     return CoalescedPermissionMessage(
         l10n_util::GetStringFUTF16(hostnames.size() == 1
                                        ? message_id_for_one_host_
diff --git a/chrome/common/extensions/permissions/permission_set_unittest.cc b/chrome/common/extensions/permissions/permission_set_unittest.cc
index e8a3f09..5070f17 100644
--- a/chrome/common/extensions/permissions/permission_set_unittest.cc
+++ b/chrome/common/extensions/permissions/permission_set_unittest.cc
@@ -69,14 +69,14 @@ std::string LegacyPermissionIDsToString(const PermissionMessageIDs& ids) {
   std::vector<std::string> strs;
   for (const PermissionMessage::ID& id : ids)
     strs.push_back(base::IntToString(id));
-  return base::StringPrintf("[ %s ]", JoinString(strs, ", ").c_str());
+  return base::StringPrintf("[ %s ]", base::JoinString(strs, ", ").c_str());
 }
 
 std::string PermissionIDsToString(const PermissionIDSet& ids) {
   std::vector<std::string> strs;
   for (const PermissionID& id : ids)
     strs.push_back(base::IntToString(id.id()));
-  return base::StringPrintf("[ %s ]", JoinString(strs, ", ").c_str());
+  return base::StringPrintf("[ %s ]", base::JoinString(strs, ", ").c_str());
 }
 
 std::string CoalescedPermissionIDsToString(
@@ -84,7 +84,7 @@ std::string CoalescedPermissionIDsToString(
   std::vector<std::string> strs;
   for (const CoalescedPermissionMessage& msg : msgs)
     strs.push_back(PermissionIDsToString(msg.permissions()));
-  return JoinString(strs, " ");
+  return base::JoinString(strs, " ");
 }
 
 // Check that the given |permissions| produce a single warning message,
diff --git a/chrome/installer/setup/update_active_setup_version_work_item.cc b/chrome/installer/setup/update_active_setup_version_work_item.cc
index 4d35494..7372675 100644
--- a/chrome/installer/setup/update_active_setup_version_work_item.cc
+++ b/chrome/installer/setup/update_active_setup_version_work_item.cc
@@ -69,5 +69,5 @@ base::string16 UpdateActiveSetupVersionWorkItem::GetUpdatedActiveSetupVersion(
     version_components[OS_UPGRADES] = base::UintToString16(previous_value + 1);
   }
 
-  return JoinString(version_components, L',');
+  return base::JoinString(version_components, L",");
 }
diff --git a/chrome/test/base/extension_js_browser_test.cc b/chrome/test/base/extension_js_browser_test.cc
index b84d223..f6396d0 100644
--- a/chrome/test/base/extension_js_browser_test.cc
+++ b/chrome/test/base/extension_js_browser_test.cc
@@ -42,7 +42,8 @@ bool ExtensionJSBrowserTest::RunJavascriptTestF(bool is_async,
   }
   scripts.push_back(BuildRunTestJSCall(is_async, "RUN_TEST_F", args));
 
-  base::string16 script_16 = JoinString(scripts, '\n');
+  base::string16 script_16 =
+      base::JoinString(scripts, base::ASCIIToUTF16("\n"));
   std::string script = base::UTF16ToUTF8(script_16);
 
   std::string result =
diff --git a/chrome/test/base/web_ui_browser_test.cc b/chrome/test/base/web_ui_browser_test.cc
index 4ba0b0b..0b9d3a5 100644
--- a/chrome/test/base/web_ui_browser_test.cc
+++ b/chrome/test/base/web_ui_browser_test.cc
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted_memory.h"
 #include "base/path_service.h"
 #include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/chrome_content_browser_client.h"
 #include "chrome/browser/profiles/profile.h"
@@ -418,7 +419,7 @@ bool WebUIBrowserTest::RunJavascriptUsingHandler(
   if (!libraries_preloaded_) {
     BuildJavascriptLibraries(&libraries);
     if (!preload_host) {
-      content = JoinString(libraries, '\n');
+      content = base::JoinString(libraries, base::ASCIIToUTF16("\n"));
       libraries.clear();
     }
   }
diff --git a/chrome/test/chromedriver/chrome_launcher.cc b/chrome/test/chromedriver/chrome_launcher.cc
index 5a79d67..9c35f8f 100644
--- a/chrome/test/chromedriver/chrome_launcher.cc
+++ b/chrome/test/chromedriver/chrome_launcher.cc
@@ -749,8 +749,8 @@ Status ProcessExtensions(const std::vector<std::string>& extensions,
   }
 
   if (extension_paths.size()) {
-    base::FilePath::StringType extension_paths_value = JoinString(
-        extension_paths, FILE_PATH_LITERAL(','));
+    base::FilePath::StringType extension_paths_value = base::JoinString(
+        extension_paths, base::FilePath::StringType(1, ','));
     UpdateExtensionSwitch(switches, "load-extension", extension_paths_value);
   }
   bg_pages->swap(bg_pages_tmp);
diff --git a/chromecast/base/metrics/cast_metrics_helper.cc b/chromecast/base/metrics/cast_metrics_helper.cc
index 6d07b4a..218da4a 100644
--- a/chromecast/base/metrics/cast_metrics_helper.cc
+++ b/chromecast/base/metrics/cast_metrics_helper.cc
@@ -78,12 +78,14 @@ std::string CastMetricsHelper::EncodeAppInfoIntoMetricsName(
     const std::string& app_id,
     const std::string& session_id,
     const std::string& sdk_version) {
-  std::vector<std::string> parts;
-  parts.push_back(action_name);
-  parts.push_back(app_id);
-  parts.push_back(session_id);
-  parts.push_back(sdk_version);
-  return JoinString(parts, kMetricsNameAppInfoDelimiter);
+  std::string result(action_name);
+  result.push_back(kMetricsNameAppInfoDelimiter);
+  result.append(app_id);
+  result.push_back(kMetricsNameAppInfoDelimiter);
+  result.append(session_id);
+  result.push_back(kMetricsNameAppInfoDelimiter);
+  result.append(sdk_version);
+  return result;
 }
 
 // static
diff --git a/chromecast/base/process_utils.cc b/chromecast/base/process_utils.cc
index 523fb1c..9e379a0 100644
--- a/chromecast/base/process_utils.cc
+++ b/chromecast/base/process_utils.cc
@@ -17,7 +17,7 @@ bool GetAppOutput(const std::vector<std::string>& argv, std::string* output) {
   DCHECK(output);
 
   // Join the args into one string, creating the command.
-  std::string command = JoinString(argv, ' ');
+  std::string command = base::JoinString(argv, " ");
 
   // Open the process.
   FILE* fp = popen(command.c_str(), "r");
diff --git a/chromeos/network/network_change_notifier_chromeos.cc b/chromeos/network/network_change_notifier_chromeos.cc
index 4561091..52ee616 100644
--- a/chromeos/network/network_change_notifier_chromeos.cc
+++ b/chromeos/network/network_change_notifier_chromeos.cc
@@ -211,9 +211,8 @@ void NetworkChangeNotifierChromeos::UpdateState(
     NET_LOG_EVENT(
         "NCNDefaultDNSServerChanged",
         base::StringPrintf(
-            "%s -> %s",
-            JoinString(dns_servers_, ",").c_str(),
-            JoinString(default_network->dns_servers(), ",").c_str()));
+            "%s -> %s", base::JoinString(dns_servers_, ",").c_str(),
+            base::JoinString(default_network->dns_servers(), ",").c_str()));
     *dns_changed = true;
   }
 
diff --git a/chromeos/network/onc/onc_validator.cc b/chromeos/network/onc/onc_validator.cc
index 4e2e732..4c2067a 100644
--- a/chromeos/network/onc/onc_validator.cc
+++ b/chromeos/network/onc/onc_validator.cc
@@ -325,7 +325,7 @@ std::string JoinStringRange(const std::vector<const char*>& strings,
                             const std::string& separator) {
   std::vector<std::string> string_vector;
   std::copy(strings.begin(), strings.end(), std::back_inserter(string_vector));
-  return JoinString(string_vector, separator);
+  return base::JoinString(string_vector, separator);
 }
 
 }  // namespace
@@ -952,7 +952,7 @@ bool Validator::ValidateCertificate(base::DictionaryValue* result) {
 }
 
 std::string Validator::MessageHeader() {
-  std::string path = path_.empty() ? "toplevel" : JoinString(path_, ".");
+  std::string path = path_.empty() ? "toplevel" : base::JoinString(path_, ".");
   std::string message = "At " + path + ": ";
   return message;
 }
diff --git a/cloud_print/virtual_driver/win/install/setup.cc b/cloud_print/virtual_driver/win/install/setup.cc
index 07aefbc..fe764a10 100644
--- a/cloud_print/virtual_driver/win/install/setup.cc
+++ b/cloud_print/virtual_driver/win/install/setup.cc
@@ -283,7 +283,7 @@ HRESULT InstallDriver(const base::FilePath& install_path) {
   driver_info.pDriverPath = const_cast<LPWSTR>(xps_path.value().c_str());
   driver_info.pConfigFile = const_cast<LPWSTR>(ui_path.value().c_str());
 
-  base::string16 dependent_files(JoinString(dependent_array, L'\n'));
+  base::string16 dependent_files(base::JoinString(dependent_array, L"\n"));
   dependent_files.push_back(L'\n');
   std::replace(dependent_files.begin(), dependent_files.end(), L'\n', L'\0');
   driver_info.pDependentFiles = &dependent_files[0];
diff --git a/components/autofill/content/browser/wallet/wallet_address.cc b/components/autofill/content/browser/wallet/wallet_address.cc
index 6fa2453..0e11196 100644
--- a/components/autofill/content/browser/wallet/wallet_address.cc
+++ b/components/autofill/content/browser/wallet/wallet_address.cc
@@ -340,7 +340,7 @@ base::string16 Address::GetInfo(const AutofillType& type,
       return recipient_name();
 
     case ADDRESS_HOME_STREET_ADDRESS:
-      return JoinString(street_address_, base::ASCIIToUTF16("\n"));
+      return base::JoinString(street_address_, base::ASCIIToUTF16("\n"));
 
     case ADDRESS_HOME_LINE1:
       return GetStreetAddressLine(0);
diff --git a/components/autofill/content/renderer/autofill_agent.cc b/components/autofill/content/renderer/autofill_agent.cc
index 3412281..ef46edb 100644
--- a/components/autofill/content/renderer/autofill_agent.cc
+++ b/components/autofill/content/renderer/autofill_agent.cc
@@ -503,7 +503,7 @@ void AutofillAgent::AcceptDataListSuggestion(
     last_part.append(suggested_value);
     parts[parts.size() - 1] = last_part;
 
-    new_value = JoinString(parts, ',');
+    new_value = base::JoinString(parts, base::ASCIIToUTF16(","));
   }
   FillFieldWithValue(new_value, input_element);
 }
diff --git a/components/autofill/content/renderer/password_form_conversion_utils_browsertest.cc b/components/autofill/content/renderer/password_form_conversion_utils_browsertest.cc
index d6b95e9..3544f4d 100644
--- a/components/autofill/content/renderer/password_form_conversion_utils_browsertest.cc
+++ b/components/autofill/content/renderer/password_form_conversion_utils_browsertest.cc
@@ -269,7 +269,8 @@ TEST_F(MAYBE_PasswordFormConversionUtilsTest, IdentifyingUsernameFields) {
         EXPECT_EQ(base::UTF8ToUTF16(cases[i].expected_username_value),
                   password_form->username_value);
         EXPECT_EQ(base::UTF8ToUTF16(cases[i].expected_other_possible_usernames),
-                  JoinString(password_form->other_possible_usernames, '+'));
+                  base::JoinString(password_form->other_possible_usernames,
+                                   base::ASCIIToUTF16("+")));
       } else {
         EXPECT_TRUE(password_form->username_value.empty());
         EXPECT_TRUE(password_form->other_possible_usernames.empty());
diff --git a/components/autofill/core/browser/address.cc b/components/autofill/core/browser/address.cc
index 9aaa3b6..389bed2 100644
--- a/components/autofill/core/browser/address.cc
+++ b/components/autofill/core/browser/address.cc
@@ -71,7 +71,7 @@ base::string16 Address::GetRawInfo(ServerFieldType type) const {
       return base::ASCIIToUTF16(country_code_);
 
     case ADDRESS_HOME_STREET_ADDRESS:
-      return JoinString(street_address_, '\n');
+      return base::JoinString(street_address_, base::ASCIIToUTF16("\n"));
 
     default:
       NOTREACHED();
diff --git a/components/autofill/core/browser/autofill_profile.cc b/components/autofill/core/browser/autofill_profile.cc
index 7012a9b..bec1121 100644
--- a/components/autofill/core/browser/autofill_profile.cc
+++ b/components/autofill/core/browser/autofill_profile.cc
@@ -328,7 +328,7 @@ base::string16 AutofillProfile::GetInfo(const AutofillType& type,
 
     std::vector<std::string> lines;
     ::i18n::addressinput::GetFormattedNationalAddress(*address_data, &lines);
-    return base::UTF8ToUTF16(JoinString(lines, '\n'));
+    return base::UTF8ToUTF16(base::JoinString(lines, "\n"));
   }
 
   const FormGroup* form_group = FormGroupForType(type);
diff --git a/components/autofill/core/browser/contact_info.cc b/components/autofill/core/browser/contact_info.cc
index 6e13759..ccb45cc 100644
--- a/components/autofill/core/browser/contact_info.cc
+++ b/components/autofill/core/browser/contact_info.cc
@@ -125,7 +125,7 @@ NameParts SplitName(const base::string16& name) {
 
   std::vector<base::string16> family_tokens(reverse_family_tokens.rbegin(),
                                             reverse_family_tokens.rend());
-  parts.family = JoinString(family_tokens, base::char16(' '));
+  parts.family = base::JoinString(family_tokens, base::ASCIIToUTF16(" "));
 
   // Take the last remaining token as the middle name (if there are at least 2
   // tokens).
@@ -135,7 +135,7 @@ NameParts SplitName(const base::string16& name) {
   }
 
   // Remainder is given name.
-  parts.given = JoinString(name_tokens, base::char16(' '));
+  parts.given = base::JoinString(name_tokens, base::ASCIIToUTF16(" "));
 
   return parts;
 }
@@ -262,7 +262,7 @@ base::string16 NameInfo::FullName() const {
   if (!family_.empty())
     full_name.push_back(family_);
 
-  return JoinString(full_name, ' ');
+  return base::JoinString(full_name, base::ASCIIToUTF16(" "));
 }
 
 base::string16 NameInfo::MiddleInitial() const {
diff --git a/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.cc b/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.cc
index e49fda7..3fed7f6 100644
--- a/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.cc
+++ b/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.cc
@@ -82,7 +82,7 @@ AutofillProfile ProfileFromSpecifics(
   std::vector<std::string> street_address(address.street_address().begin(),
                                           address.street_address().end());
   profile.SetRawInfo(ADDRESS_HOME_STREET_ADDRESS,
-                     base::UTF8ToUTF16(JoinString(street_address, '\n')));
+                     base::UTF8ToUTF16(base::JoinString(street_address, "\n")));
 
   profile.SetRawInfo(COMPANY_NAME, base::UTF8ToUTF16(address.company_name()));
   profile.SetRawInfo(ADDRESS_HOME_STATE,
diff --git a/components/autofill/core/common/password_form.cc b/components/autofill/core/common/password_form.cc
index fdd6144..0f369db 100644
--- a/components/autofill/core/common/password_form.cc
+++ b/components/autofill/core/common/password_form.cc
@@ -36,7 +36,8 @@ void PasswordFormToJSON(const PasswordForm& form,
   target->SetBoolean("new_password_marked_by_site",
                      form.new_password_marked_by_site);
   target->SetString("other_possible_usernames",
-                    JoinString(form.other_possible_usernames, '|'));
+                    base::JoinString(form.other_possible_usernames,
+                                     base::ASCIIToUTF16("|")));
   target->SetBoolean("blacklisted", form.blacklisted_by_user);
   target->SetBoolean("preferred", form.preferred);
   target->SetBoolean("ssl_valid", form.ssl_valid);
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_unittest.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_unittest.cc
index 12e1591..05edc7b 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_unittest.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_unittest.cc
@@ -527,7 +527,7 @@ TEST_F(DataReductionProxyConfigTest, AreProxiesBypassed) {
     if (tests[i].allowed && tests[i].fallback_allowed)
       proxies.push_back(fallback_origin);
 
-    std::string proxy_rules = "http=" + JoinString(proxies, ",") +
+    std::string proxy_rules = "http=" + base::JoinString(proxies, ",") +
                               ",direct://;" + "https=" + ssl_origin +
                               ",direct://;";
 
@@ -578,7 +578,8 @@ TEST_F(DataReductionProxyConfigTest, AreProxiesBypassedRetryDelay) {
   proxies.push_back(origin);
   proxies.push_back(fallback_origin);
 
-  std::string proxy_rules = "http=" + JoinString(proxies, ",") + ",direct://;";
+  std::string proxy_rules =
+      "http=" + base::JoinString(proxies, ",") + ",direct://;";
 
   rules.ParseFromString(proxy_rules);
 
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_configurator.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_configurator.cc
index 9bfd9bd..f39d95e 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_configurator.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_configurator.cc
@@ -63,7 +63,7 @@ void DataReductionProxyConfigurator::Enable(
   }
 
   config.proxy_rules().bypass_rules.ParseFromString(
-      JoinString(bypass_rules_, ", "));
+      base::JoinString(bypass_rules_, ", "));
   // The ID is set to a bogus value. It cannot be left uninitialized, else the
   // config will return invalid.
   net::ProxyConfig::ID unused_id = 1;
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.cc
index 8717fcb..6a55084 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.cc
@@ -398,7 +398,7 @@ void DataReductionProxyRequestOptions::RegenerateRequestHeaderValue() {
   for (const auto& experiment : experiments_)
     headers.push_back(FormatOption(kExperimentsOption, experiment));
 
-  header_value_ = JoinString(headers, ", ");
+  header_value_ = base::JoinString(headers, ", ");
 }
 
 }  // namespace data_reduction_proxy
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options_unittest.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options_unittest.cc
index 99eb96e..a48459f 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options_unittest.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options_unittest.cc
@@ -129,7 +129,7 @@ void SetHeaderExpectations(const std::string& session,
         std::string(kExperimentsOption) + "=" + experiment);
   }
   if (!expected_options.empty())
-    *expected_header = JoinString(expected_options, ", ");
+    *expected_header = base::JoinString(expected_options, ", ");
 }
 
 }  // namespace
diff --git a/components/history/core/browser/top_sites_database.cc b/components/history/core/browser/top_sites_database.cc
index 74ab115..d1f024d 100644
--- a/components/history/core/browser/top_sites_database.cc
+++ b/components/history/core/browser/top_sites_database.cc
@@ -85,7 +85,7 @@ std::string GetRedirects(const MostVisitedURL& url) {
   std::vector<std::string> redirects;
   for (size_t i = 0; i < url.redirects.size(); i++)
     redirects.push_back(url.redirects[i].spec());
-  return JoinString(redirects, ' ');
+  return base::JoinString(redirects, " ");
 }
 
 // Decodes redirects from a string and sets them for the url.
diff --git a/components/nacl/renderer/platform_info.cc b/components/nacl/renderer/platform_info.cc
index 712526c..22edf18 100644
--- a/components/nacl/renderer/platform_info.cc
+++ b/components/nacl/renderer/platform_info.cc
@@ -75,7 +75,7 @@ std::string GetCpuFeatures() {
   else if (cpu.has_sse2()) features.push_back("+sse2");
 
   // TODO: AES, POPCNT, LZCNT, ...
-  return JoinString(features, ',');
+  return base::JoinString(features, ",");
 }
 
 }  // namespace nacl
diff --git a/components/policy/core/browser/policy_error_map.cc b/components/policy/core/browser/policy_error_map.cc
index 04411b6..3360c3d 100644
--- a/components/policy/core/browser/policy_error_map.cc
+++ b/components/policy/core/browser/policy_error_map.cc
@@ -186,7 +186,7 @@ base::string16 PolicyErrorMap::GetErrors(const std::string& policy) {
   std::vector<base::string16> list;
   for (const_iterator it = range.first; it != range.second; ++it)
     list.push_back(it->second);
-  return JoinString(list, '\n');
+  return base::JoinString(list, base::ASCIIToUTF16("\n"));
 }
 
 bool PolicyErrorMap::empty() {
diff --git a/components/proximity_auth/cryptauth/cryptauth_gcm_manager_impl.cc b/components/proximity_auth/cryptauth/cryptauth_gcm_manager_impl.cc
index 7c07fc2..834e42a 100644
--- a/components/proximity_auth/cryptauth/cryptauth_gcm_manager_impl.cc
+++ b/components/proximity_auth/cryptauth/cryptauth_gcm_manager_impl.cc
@@ -93,7 +93,7 @@ void CryptAuthGCMManagerImpl::OnMessage(const std::string& app_id,
   PA_LOG(INFO) << "GCM message received:\n"
                << "  sender_id: " << message.sender_id << "\n"
                << "  collapse_key: " << message.collapse_key << "\n"
-               << "  data:\n    " << JoinString(fields, "\n    ");
+               << "  data:\n    " << base::JoinString(fields, "\n    ");
 
   if (message.data.find(kRegistrationTickleTypeKey) == message.data.end()) {
     PA_LOG(WARNING) << "GCM message does not contain 'registrationTickleType'.";
diff --git a/components/search_engines/default_search_policy_handler.cc b/components/search_engines/default_search_policy_handler.cc
index 573af72..38df010 100644
--- a/components/search_engines/default_search_policy_handler.cc
+++ b/components/search_engines/default_search_policy_handler.cc
@@ -169,7 +169,7 @@ void DefaultSearchEncodingsPolicyHandler::ApplyPolicySettings(
       string_parts.push_back(s);
     }
   }
-  std::string encodings = JoinString(string_parts, ';');
+  std::string encodings = base::JoinString(string_parts, ";");
   prefs->SetString(prefs::kDefaultSearchProviderEncodings, encodings);
 }
 
diff --git a/components/search_engines/default_search_pref_migration_unittest.cc b/components/search_engines/default_search_pref_migration_unittest.cc
index 6d1b6ea..73d9d0b 100644
--- a/components/search_engines/default_search_pref_migration_unittest.cc
+++ b/components/search_engines/default_search_pref_migration_unittest.cc
@@ -91,7 +91,7 @@ void DefaultSearchPrefMigrationTest::SaveDefaultSearchProviderToLegacyPrefs(
     GURL icon_gurl = t_url->favicon_url();
     if (!icon_gurl.is_empty())
       icon_url = icon_gurl.spec();
-    encodings = JoinString(t_url->input_encodings(), ';');
+    encodings = base::JoinString(t_url->input_encodings(), ";");
     short_name = base::UTF16ToUTF8(t_url->short_name());
     keyword = base::UTF16ToUTF8(t_url->keyword());
     id_string = base::Int64ToString(t_url->id());
diff --git a/components/search_engines/keyword_table.cc b/components/search_engines/keyword_table.cc
index 7de6217..a4ad483 100644
--- a/components/search_engines/keyword_table.cc
+++ b/components/search_engines/keyword_table.cc
@@ -80,7 +80,7 @@ const std::string ColumnsForVersion(int version, bool concatenated) {
     columns.push_back("new_tab_url");
   }
 
-  return JoinString(columns, std::string(concatenated ? " || " : ", "));
+  return base::JoinString(columns, std::string(concatenated ? " || " : ", "));
 }
 
 
@@ -115,7 +115,8 @@ void BindURLToStatement(const TemplateURLData& data,
       std::string());
   s->BindInt64(starting_column + 6, data.date_created.ToTimeT());
   s->BindInt(starting_column + 7, data.usage_count);
-  s->BindString(starting_column + 8, JoinString(data.input_encodings, ';'));
+  s->BindString(starting_column + 8,
+                base::JoinString(data.input_encodings, ";"));
   s->BindBool(starting_column + 9, data.show_in_default_list);
   s->BindString(starting_column + 10, data.suggestions_url);
   s->BindInt(starting_column + 11, data.prepopulate_id);
diff --git a/components/search_engines/template_url.cc b/components/search_engines/template_url.cc
index 8202fa4..dbb74fc 100644
--- a/components/search_engines/template_url.cc
+++ b/components/search_engines/template_url.cc
@@ -337,7 +337,7 @@ std::string TemplateURLRef::ReplaceSearchTerms(
     return url;
 
   GURL::Replacements replacements;
-  std::string query_str = JoinString(query_params, "&");
+  std::string query_str = base::JoinString(query_params, "&");
   replacements.SetQueryStr(query_str);
   return gurl.ReplaceComponents(replacements).possibly_invalid_spec();
 }
diff --git a/components/search_engines/template_url_service.cc b/components/search_engines/template_url_service.cc
index 7ba2ff0..12abbe8 100644
--- a/components/search_engines/template_url_service.cc
+++ b/components/search_engines/template_url_service.cc
@@ -1197,7 +1197,8 @@ syncer::SyncData TemplateURLService::CreateSyncDataFromTemplateURL(
   se_specifics->set_safe_for_autoreplace(turl.safe_for_autoreplace());
   se_specifics->set_originating_url(turl.originating_url().spec());
   se_specifics->set_date_created(turl.date_created().ToInternalValue());
-  se_specifics->set_input_encodings(JoinString(turl.input_encodings(), ';'));
+  se_specifics->set_input_encodings(
+      base::JoinString(turl.input_encodings(), ";"));
   se_specifics->set_show_in_default_list(turl.show_in_default_list());
   se_specifics->set_suggestions_url(turl.suggestions_url());
   se_specifics->set_prepopulate_id(turl.prepopulate_id());
diff --git a/components/search_engines/template_url_service_sync_unittest.cc b/components/search_engines/template_url_service_sync_unittest.cc
index 66a6123..d411256 100644
--- a/components/search_engines/template_url_service_sync_unittest.cc
+++ b/components/search_engines/template_url_service_sync_unittest.cc
@@ -68,7 +68,8 @@ syncer::SyncData CreateCustomSyncData(const TemplateURL& turl,
   se_specifics->set_safe_for_autoreplace(turl.safe_for_autoreplace());
   se_specifics->set_originating_url(turl.originating_url().spec());
   se_specifics->set_date_created(turl.date_created().ToInternalValue());
-  se_specifics->set_input_encodings(JoinString(turl.input_encodings(), ';'));
+  se_specifics->set_input_encodings(
+      base::JoinString(turl.input_encodings(), ";"));
   se_specifics->set_show_in_default_list(turl.show_in_default_list());
   se_specifics->set_suggestions_url(turl.suggestions_url());
   se_specifics->set_prepopulate_id(turl.prepopulate_id());
diff --git a/components/signin/core/browser/gaia_cookie_manager_service.cc b/components/signin/core/browser/gaia_cookie_manager_service.cc
index 4beff36..dcc74ae 100644
--- a/components/signin/core/browser/gaia_cookie_manager_service.cc
+++ b/components/signin/core/browser/gaia_cookie_manager_service.cc
@@ -114,7 +114,7 @@ GaiaCookieManagerService::ExternalCcResultFetcher::GetExternalCcResult() {
        ++it) {
     results.push_back(it->first + ":" + it->second);
   }
-  return JoinString(results, ",");
+  return base::JoinString(results, ",");
 }
 
 void GaiaCookieManagerService::ExternalCcResultFetcher::Start() {
diff --git a/components/translate/core/browser/translate_prefs.cc b/components/translate/core/browser/translate_prefs.cc
index 768be0e..24547005 100644
--- a/components/translate/core/browser/translate_prefs.cc
+++ b/components/translate/core/browser/translate_prefs.cc
@@ -326,7 +326,7 @@ void TranslatePrefs::GetLanguageList(std::vector<std::string>* languages) {
 void TranslatePrefs::UpdateLanguageList(
     const std::vector<std::string>& languages) {
 #if defined(OS_CHROMEOS)
-  std::string languages_str = JoinString(languages, ',');
+  std::string languages_str = base::JoinString(languages, ",");
   prefs_->SetString(preferred_languages_pref_.c_str(), languages_str);
 #endif
 
@@ -335,7 +335,7 @@ void TranslatePrefs::UpdateLanguageList(
   // some web sites don't understand 'en-US' but 'en'. See crosbug.com/9884.
   std::vector<std::string> accept_languages;
   ExpandLanguageCodes(languages, &accept_languages);
-  std::string accept_languages_str = JoinString(accept_languages, ',');
+  std::string accept_languages_str = base::JoinString(accept_languages, ",");
   prefs_->SetString(accept_languages_pref_.c_str(), accept_languages_str);
 }
 
@@ -485,7 +485,8 @@ void TranslatePrefs::MigrateUserPrefs(PrefService* user_prefs,
         accept_languages.push_back(lang);
     }
 
-    std::string new_accept_languages_str = JoinString(accept_languages, ",");
+    std::string new_accept_languages_str =
+        base::JoinString(accept_languages, ",");
     user_prefs->SetString(accept_languages_pref, new_accept_languages_str);
   }
 }
diff --git a/components/view_manager/gesture_manager_unittest.cc b/components/view_manager/gesture_manager_unittest.cc
index cc180b3..feece31 100644
--- a/components/view_manager/gesture_manager_unittest.cc
+++ b/components/view_manager/gesture_manager_unittest.cc
@@ -108,7 +108,7 @@ class TestGestureManagerDelegate : public GestureManagerDelegate {
   ~TestGestureManagerDelegate() override {}
 
   std::string GetAndClearDescriptions() {
-    const std::string result(JoinString(descriptions_, '\n'));
+    const std::string result(base::JoinString(descriptions_, "\n"));
     descriptions_.clear();
     return result;
   }
diff --git a/components/view_manager/test_change_tracker.cc b/components/view_manager/test_change_tracker.cc
index 33e0f96..ac7183d 100644
--- a/components/view_manager/test_change_tracker.cc
+++ b/components/view_manager/test_change_tracker.cc
@@ -133,7 +133,7 @@ std::string ChangeViewDescription(const std::vector<Change>& changes) {
   std::vector<std::string> view_strings(changes[0].views.size());
   for (size_t i = 0; i < changes[0].views.size(); ++i)
     view_strings[i] = "[" + changes[0].views[i].ToString() + "]";
-  return JoinString(view_strings, ',');
+  return base::JoinString(view_strings, ",");
 }
 
 TestView ViewDataToTestView(const ViewDataPtr& data) {
diff --git a/content/browser/accessibility/accessibility_tree_formatter_utils_win.cc b/content/browser/accessibility/accessibility_tree_formatter_utils_win.cc
index 063f5cd..0355078 100644
--- a/content/browser/accessibility/accessibility_tree_formatter_utils_win.cc
+++ b/content/browser/accessibility/accessibility_tree_formatter_utils_win.cc
@@ -11,6 +11,7 @@
 
 #include "base/memory/singleton.h"
 #include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #include "third_party/iaccessible2/ia2_api_all.h"
 
 namespace content {
@@ -314,7 +315,7 @@ void IAccessibleStateToStringVector(int32 ia_state,
 base::string16 IAccessibleStateToString(int32 ia_state) {
   std::vector<base::string16> strings;
   IAccessibleStateToStringVector(ia_state, &strings);
-  return JoinString(strings, ',');
+  return base::JoinString(strings, base::ASCIIToUTF16(","));
 }
 
 void IAccessible2StateToStringVector(int32 ia2_state,
@@ -331,7 +332,7 @@ void IAccessible2StateToStringVector(int32 ia2_state,
 base::string16 IAccessible2StateToString(int32 ia2_state) {
   std::vector<base::string16> strings;
   IAccessible2StateToStringVector(ia2_state, &strings);
-  return JoinString(strings, ',');
+  return base::JoinString(strings, base::ASCIIToUTF16(","));
 }
 
 base::string16 AccessibilityEventToString(int32 event_id) {
diff --git a/content/browser/accessibility/dump_accessibility_browsertest_base.cc b/content/browser/accessibility/dump_accessibility_browsertest_base.cc
index f6da92c..2a9a1ef 100644
--- a/content/browser/accessibility/dump_accessibility_browsertest_base.cc
+++ b/content/browser/accessibility/dump_accessibility_browsertest_base.cc
@@ -202,7 +202,7 @@ void DumpAccessibilityTestBase::RunTest(
   // file length differences are found.
   expected_lines.push_back(kMarkEndOfFile);
   actual_lines.push_back(kMarkEndOfFile);
-  std::string actual_contents = JoinString(actual_lines, "\n");
+  std::string actual_contents = base::JoinString(actual_lines, "\n");
 
   std::vector<int> diff_lines = DiffLines(expected_lines, actual_lines);
   bool is_different = diff_lines.size() > 0;
diff --git a/content/browser/gpu/gpu_data_manager_impl_private.cc b/content/browser/gpu/gpu_data_manager_impl_private.cc
index 87bad09..3c25275 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.cc
+++ b/content/browser/gpu/gpu_data_manager_impl_private.cc
@@ -566,7 +566,7 @@ void GpuDataManagerImplPrivate::UpdateGpuInfoHelper() {
         gpu::GpuControlList::kOsAny, std::string(), gpu_info_);
 
     disabled_extensions_ =
-        JoinString(gpu_driver_bug_list_->GetDisabledExtensions(), ' ');
+        base::JoinString(gpu_driver_bug_list_->GetDisabledExtensions(), " ");
   }
   gpu::GpuDriverBugList::AppendWorkaroundsFromCommandLine(
       &gpu_driver_bugs_, *base::CommandLine::ForCurrentProcess());
diff --git a/content/browser/renderer_host/pepper/pepper_socket_utils.cc b/content/browser/renderer_host/pepper/pepper_socket_utils.cc
index 45d35ce..718eec2 100644
--- a/content/browser/renderer_host/pepper/pepper_socket_utils.cc
+++ b/content/browser/renderer_host/pepper/pepper_socket_utils.cc
@@ -81,10 +81,11 @@ bool GetCertificateFields(const net::X509Certificate& cert,
                    new base::StringValue(issuer.country_name));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_ISSUER_ORGANIZATION_NAME,
-      new base::StringValue(JoinString(issuer.organization_names, '\n')));
+      new base::StringValue(base::JoinString(issuer.organization_names, "\n")));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_ISSUER_ORGANIZATION_UNIT_NAME,
-      new base::StringValue(JoinString(issuer.organization_unit_names, '\n')));
+      new base::StringValue(
+          base::JoinString(issuer.organization_unit_names, "\n")));
 
   const net::CertPrincipal& subject = cert.subject();
   fields->SetField(PP_X509CERTIFICATE_PRIVATE_SUBJECT_COMMON_NAME,
@@ -97,10 +98,12 @@ bool GetCertificateFields(const net::X509Certificate& cert,
                    new base::StringValue(subject.country_name));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_SUBJECT_ORGANIZATION_NAME,
-      new base::StringValue(JoinString(subject.organization_names, '\n')));
+      new base::StringValue(
+          base::JoinString(subject.organization_names, "\n")));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_SUBJECT_ORGANIZATION_UNIT_NAME,
-      new base::StringValue(JoinString(subject.organization_unit_names, '\n')));
+      new base::StringValue(
+          base::JoinString(subject.organization_unit_names, "\n")));
 
   const std::string& serial_number = cert.serial_number();
   fields->SetField(PP_X509CERTIFICATE_PRIVATE_SERIAL_NUMBER,
diff --git a/content/browser/renderer_host/pepper/pepper_tcp_socket.cc b/content/browser/renderer_host/pepper/pepper_tcp_socket.cc
index 8d590f7..16b19b2 100644
--- a/content/browser/renderer_host/pepper/pepper_tcp_socket.cc
+++ b/content/browser/renderer_host/pepper/pepper_tcp_socket.cc
@@ -313,10 +313,11 @@ bool PepperTCPSocket::GetCertificateFields(
                    new base::StringValue(issuer.country_name));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_ISSUER_ORGANIZATION_NAME,
-      new base::StringValue(JoinString(issuer.organization_names, '\n')));
+      new base::StringValue(base::JoinString(issuer.organization_names, "\n")));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_ISSUER_ORGANIZATION_UNIT_NAME,
-      new base::StringValue(JoinString(issuer.organization_unit_names, '\n')));
+      new base::StringValue(
+          base::JoinString(issuer.organization_unit_names, "\n")));
 
   const net::CertPrincipal& subject = cert.subject();
   fields->SetField(PP_X509CERTIFICATE_PRIVATE_SUBJECT_COMMON_NAME,
@@ -329,10 +330,12 @@ bool PepperTCPSocket::GetCertificateFields(
                    new base::StringValue(subject.country_name));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_SUBJECT_ORGANIZATION_NAME,
-      new base::StringValue(JoinString(subject.organization_names, '\n')));
+      new base::StringValue(
+          base::JoinString(subject.organization_names, "\n")));
   fields->SetField(
       PP_X509CERTIFICATE_PRIVATE_SUBJECT_ORGANIZATION_UNIT_NAME,
-      new base::StringValue(JoinString(subject.organization_unit_names, '\n')));
+      new base::StringValue(
+          base::JoinString(subject.organization_unit_names, "\n")));
 
   const std::string& serial_number = cert.serial_number();
   fields->SetField(PP_X509CERTIFICATE_PRIVATE_SERIAL_NUMBER,
diff --git a/content/browser/renderer_host/websocket_host.cc b/content/browser/renderer_host/websocket_host.cc
index 8d0046b..3c89b5c 100644
--- a/content/browser/renderer_host/websocket_host.cc
+++ b/content/browser/renderer_host/websocket_host.cc
@@ -353,7 +353,7 @@ void WebSocketHost::OnAddChannelRequest(
   DVLOG(3) << "WebSocketHost::OnAddChannelRequest"
            << " routing_id=" << routing_id_ << " socket_url=\"" << socket_url
            << "\" requested_protocols=\""
-           << JoinString(requested_protocols, ", ") << "\" origin=\""
+           << base::JoinString(requested_protocols, ", ") << "\" origin=\""
            << origin.string() << "\"";
 
   DCHECK(!channel_);
@@ -377,7 +377,7 @@ void WebSocketHost::AddChannel(
   DVLOG(3) << "WebSocketHost::AddChannel"
            << " routing_id=" << routing_id_ << " socket_url=\"" << socket_url
            << "\" requested_protocols=\""
-           << JoinString(requested_protocols, ", ") << "\" origin=\""
+           << base::JoinString(requested_protocols, ", ") << "\" origin=\""
            << origin.string() << "\"";
 
   DCHECK(!channel_);
diff --git a/content/browser/speech/google_one_shot_remote_engine.cc b/content/browser/speech/google_one_shot_remote_engine.cc
index 92e4cb3..48afc80 100644
--- a/content/browser/speech/google_one_shot_remote_engine.cc
+++ b/content/browser/speech/google_one_shot_remote_engine.cc
@@ -205,7 +205,8 @@ void GoogleOneShotRemoteEngine::StartRecognition() {
   std::string api_key = google_apis::GetAPIKey();
   parts.push_back("key=" + net::EscapeQueryParamValue(api_key, true));
 
-  GURL url(std::string(kDefaultSpeechRecognitionUrl) + JoinString(parts, '&'));
+  GURL url(std::string(kDefaultSpeechRecognitionUrl) +
+           base::JoinString(parts, "&"));
 
   encoder_.reset(AudioEncoder::Create(kDefaultAudioCodec,
                                       config_.audio_sample_rate,
diff --git a/content/browser/speech/google_streaming_remote_engine.cc b/content/browser/speech/google_streaming_remote_engine.cc
index fc8c6d2..0082cec 100644
--- a/content/browser/speech/google_streaming_remote_engine.cc
+++ b/content/browser/speech/google_streaming_remote_engine.cc
@@ -320,7 +320,7 @@ GoogleStreamingRemoteEngine::ConnectBothStreams(const FSMEventArgs&) {
   downstream_args.push_back("output=pb");
   GURL downstream_url(std::string(kWebServiceBaseUrl) +
                       std::string(kDownstreamUrl) +
-                      JoinString(downstream_args, '&'));
+                      base::JoinString(downstream_args, "&"));
 
   downstream_fetcher_ = URLFetcher::Create(
       kDownstreamUrlFetcherIdForTesting, downstream_url, URLFetcher::GET, this);
@@ -372,7 +372,7 @@ GoogleStreamingRemoteEngine::ConnectBothStreams(const FSMEventArgs&) {
   }
   GURL upstream_url(std::string(kWebServiceBaseUrl) +
                     std::string(kUpstreamUrl) +
-                    JoinString(upstream_args, '&'));
+                    base::JoinString(upstream_args, "&"));
 
   upstream_fetcher_ = URLFetcher::Create(kUpstreamUrlFetcherIdForTesting,
                                          upstream_url, URLFetcher::POST, this);
diff --git a/content/child/websocket_bridge.cc b/content/child/websocket_bridge.cc
index a5cca24..6893937 100644
--- a/content/child/websocket_bridge.cc
+++ b/content/child/websocket_bridge.cc
@@ -220,7 +220,7 @@ void WebSocketBridge::connect(
   url::DeprecatedSerializedOrigin origin_to_pass(origin);
 
   DVLOG(1) << "Bridge#" << channel_id_ << " Connect(" << url << ", ("
-           << JoinString(protocols_to_pass, ", ") << "), "
+           << base::JoinString(protocols_to_pass, ", ") << "), "
            << origin_to_pass.string() << ")";
 
   ChildThreadImpl::current()->Send(new WebSocketHostMsg_AddChannelRequest(
diff --git a/extensions/browser/api/bluetooth/bluetooth_private_api.cc b/extensions/browser/api/bluetooth/bluetooth_private_api.cc
index 1fd4870..0ac112a 100644
--- a/extensions/browser/api/bluetooth/bluetooth_private_api.cc
+++ b/extensions/browser/api/bluetooth/bluetooth_private_api.cc
@@ -227,7 +227,7 @@ void BluetoothPrivateSetAdapterStateFunction::SendError() {
             std::back_inserter(failed_vector));
 
   std::vector<std::string> replacements(1);
-  replacements[0] = JoinString(failed_vector, ", ");
+  replacements[0] = base::JoinString(failed_vector, ", ");
   std::string error =
       ReplaceStringPlaceholders(kSetAdapterPropertyError, replacements, NULL);
   SetError(error);
diff --git a/extensions/browser/api/management/management_api.cc b/extensions/browser/api/management/management_api.cc
index 468c0c5..1581414 100644
--- a/extensions/browser/api/management/management_api.cc
+++ b/extensions/browser/api/management/management_api.cc
@@ -499,7 +499,7 @@ void ManagementSetEnabledFunction::OnRequirementsChecked(
   } else {
     // TODO(devlin): Should we really be noisy here all the time?
     Respond(Error(keys::kMissingRequirementsError,
-                  JoinString(requirements_errors, ' ')));
+                  base::JoinString(requirements_errors, " ")));
   }
 }
 
diff --git a/extensions/browser/api/vpn_provider/vpn_provider_api.cc b/extensions/browser/api/vpn_provider/vpn_provider_api.cc
index 069f171..e3b80ae 100644
--- a/extensions/browser/api/vpn_provider/vpn_provider_api.cc
+++ b/extensions/browser/api/vpn_provider/vpn_provider_api.cc
@@ -112,13 +112,14 @@ void ConvertParameters(const api_vpn::Parameters& parameters,
   parameter_value->SetStringWithoutPathExpansion(
       shill::kSubnetPrefixParameterThirdPartyVpn, cidr_parts[1]);
 
+  std::string ip_delimiter(1, shill::kIPDelimiter);
   parameter_value->SetStringWithoutPathExpansion(
       shill::kExclusionListParameterThirdPartyVpn,
-      JoinString(parameters.exclusion_list, shill::kIPDelimiter));
+      base::JoinString(parameters.exclusion_list, ip_delimiter));
 
   parameter_value->SetStringWithoutPathExpansion(
       shill::kInclusionListParameterThirdPartyVpn,
-      JoinString(parameters.inclusion_list, shill::kIPDelimiter));
+      base::JoinString(parameters.inclusion_list, ip_delimiter));
 
   if (parameters.mtu) {
     parameter_value->SetStringWithoutPathExpansion(
@@ -131,15 +132,16 @@ void ConvertParameters(const api_vpn::Parameters& parameters,
         *parameters.broadcast_address);
   }
 
+  std::string non_ip_delimiter(1, shill::kNonIPDelimiter);
   if (parameters.domain_search) {
     parameter_value->SetStringWithoutPathExpansion(
         shill::kDomainSearchParameterThirdPartyVpn,
-        JoinString(*parameters.domain_search, shill::kNonIPDelimiter));
+        base::JoinString(*parameters.domain_search, non_ip_delimiter));
   }
 
   parameter_value->SetStringWithoutPathExpansion(
       shill::kDnsServersParameterThirdPartyVpn,
-      JoinString(parameters.dns_servers, shill::kIPDelimiter));
+      base::JoinString(parameters.dns_servers, ip_delimiter));
 
   return;
 }
diff --git a/extensions/browser/content_verifier.cc b/extensions/browser/content_verifier.cc
index 3bbe4a9..b85e8ee 100644
--- a/extensions/browser/content_verifier.cc
+++ b/extensions/browser/content_verifier.cc
@@ -124,7 +124,8 @@ static base::FilePath MakeImagePathRelative(const base::FilePath& path) {
 
   // Note that elsewhere we always normalize path separators to '/' so this
   // should work for all platforms.
-  return base::FilePath(JoinString(parts, '/'));
+  return base::FilePath(
+      base::JoinString(parts, base::FilePath::StringType(1, '/')));
 }
 
 void ContentVerifier::OnExtensionLoaded(
diff --git a/extensions/browser/updater/extension_downloader.cc b/extensions/browser/updater/extension_downloader.cc
index a038ebb..d1d6468 100644
--- a/extensions/browser/updater/extension_downloader.cc
+++ b/extensions/browser/updater/extension_downloader.cc
@@ -136,7 +136,7 @@ bool IncrementAuthUserIndex(GURL* url) {
     return false;
   new_query_parts.push_back(
       base::StringPrintf("%s=%d", kAuthUserQueryKey, user_index + 1));
-  std::string new_query_string = JoinString(new_query_parts, '&');
+  std::string new_query_string = base::JoinString(new_query_parts, "&");
   url::Component new_query(0, new_query_string.size());
   url::Replacements<char> replacements;
   replacements.SetQuery(new_query_string.c_str(), new_query);
@@ -469,7 +469,7 @@ void ExtensionDownloader::CreateManifestFetcher() {
     std::vector<std::string> id_vector(
         manifests_queue_.active_request()->extension_ids().begin(),
         manifests_queue_.active_request()->extension_ids().end());
-    std::string id_list = JoinString(id_vector, ',');
+    std::string id_list = base::JoinString(id_vector, ",");
     VLOG(2) << "Fetching " << manifests_queue_.active_request()->full_url()
             << " for " << id_list;
   }
diff --git a/extensions/browser/updater/manifest_fetch_data.cc b/extensions/browser/updater/manifest_fetch_data.cc
index 6511a1e..f72f32e 100644
--- a/extensions/browser/updater/manifest_fetch_data.cc
+++ b/extensions/browser/updater/manifest_fetch_data.cc
@@ -143,7 +143,8 @@ bool ManifestFetchData::AddExtension(const std::string& id,
   }
 
   std::string extra = full_url_.has_query() ? "&" : "?";
-  extra += "x=" + net::EscapeQueryParamValue(JoinString(parts, '&'), true);
+  extra +=
+      "x=" + net::EscapeQueryParamValue(base::JoinString(parts, "&"), true);
 
   // Check against our max url size, exempting the first extension added.
   int new_size = full_url_.possibly_invalid_spec().size() + extra.size();
diff --git a/extensions/common/api/sockets/sockets_manifest_permission.cc b/extensions/common/api/sockets/sockets_manifest_permission.cc
index 0f7613e..6dbd4fc 100644
--- a/extensions/common/api/sockets/sockets_manifest_permission.cc
+++ b/extensions/common/api/sockets/sockets_manifest_permission.cc
@@ -131,9 +131,9 @@ void AddSubdomainHostMessage(const SocketPermissionEntrySet& sockets,
       messages->push_back(PermissionMessage(
           PermissionMessage::kSocketDomainHosts,
           l10n_util::GetStringFUTF16(
-              id, JoinString(std::vector<base::string16>(domains.begin(),
-                                                         domains.end()),
-                             ' '))));
+              id, base::JoinString(std::vector<base::string16>(domains.begin(),
+                                                               domains.end()),
+                                   base::ASCIIToUTF16(" ")))));
     }
     if (ids) {
       for (const auto& domain : domains)
@@ -163,9 +163,9 @@ void AddSpecificHostMessage(const SocketPermissionEntrySet& sockets,
       messages->push_back(PermissionMessage(
           PermissionMessage::kSocketSpecificHosts,
           l10n_util::GetStringFUTF16(
-              id, JoinString(std::vector<base::string16>(hostnames.begin(),
-                                                         hostnames.end()),
-                             ' '))));
+              id, base::JoinString(std::vector<base::string16>(
+                                       hostnames.begin(), hostnames.end()),
+                                   base::ASCIIToUTF16(" ")))));
     }
     if (ids) {
       for (const auto& hostname : hostnames)
diff --git a/extensions/common/csp_validator.cc b/extensions/common/csp_validator.cc
index 06ea4ef..a984e3d 100644
--- a/extensions/common/csp_validator.cc
+++ b/extensions/common/csp_validator.cc
@@ -297,7 +297,7 @@ std::string SanitizeContentSecurityPolicy(
     }
   }
 
-  return JoinString(sane_csp_parts, ' ');
+  return base::JoinString(sane_csp_parts, " ");
 }
 
 bool ContentSecurityPolicyIsSandboxed(
diff --git a/extensions/common/features/base_feature_provider.cc b/extensions/common/features/base_feature_provider.cc
index 9d24d84..472e1f55 100644
--- a/extensions/common/features/base_feature_provider.cc
+++ b/extensions/common/features/base_feature_provider.cc
@@ -62,7 +62,7 @@ BaseFeatureProvider::BaseFeatureProvider(const base::DictionaryValue& root,
       std::stack<std::pair<std::string, const base::DictionaryValue*> >
           parse_stack;
       while (!split.empty()) {
-        std::string parent_name = JoinString(split, '.');
+        std::string parent_name = base::JoinString(split, ".");
         split.pop_back();
         if (root.HasKey(parent_name)) {
           const base::DictionaryValue* parent = nullptr;
@@ -176,7 +176,7 @@ Feature* BaseFeatureProvider::GetParent(Feature* feature) const {
   if (split.size() < 2)
     return nullptr;
   split.pop_back();
-  return GetFeature(JoinString(split, '.'));
+  return GetFeature(base::JoinString(split, "."));
 }
 
 // Children of a given API are named starting with parent.name()+".", which
diff --git a/extensions/common/permissions/permission_message_test_util.cc b/extensions/common/permissions/permission_message_test_util.cc
index 47e9913..32890fd 100644
--- a/extensions/common/permissions/permission_message_test_util.cc
+++ b/extensions/common/permissions/permission_message_test_util.cc
@@ -102,7 +102,7 @@ base::string16 MessagesVectorToString(
   if (messages.empty())
     return base::ASCIIToUTF16("\n");
   return base::ASCIIToUTF16("\"") +
-         JoinString(messages, base::ASCIIToUTF16("\"\n\"")) +
+         base::JoinString(messages, base::ASCIIToUTF16("\"\n\"")) +
          base::ASCIIToUTF16("\"\n");
 }
 
diff --git a/extensions/common/permissions/socket_permission_entry.cc b/extensions/common/permissions/socket_permission_entry.cc
index 6adf307..8b2d355 100644
--- a/extensions/common/permissions/socket_permission_entry.cc
+++ b/extensions/common/permissions/socket_permission_entry.cc
@@ -178,7 +178,7 @@ bool SocketPermissionEntry::ParseHostPattern(
     } else {
       result.match_subdomains_ = false;
     }
-    result.pattern_.host = JoinString(host_components, kDot);
+    result.pattern_.host = base::JoinString(host_components, ".");
   }
 
   if (pattern_tokens.size() == 1 || pattern_tokens[1].empty() ||
diff --git a/extensions/common/permissions/usb_device_permission.cc b/extensions/common/permissions/usb_device_permission.cc
index 4384b32..59b28d5 100644
--- a/extensions/common/permissions/usb_device_permission.cc
+++ b/extensions/common/permissions/usb_device_permission.cc
@@ -117,11 +117,11 @@ void AddPermissionsToLists(const std::set<UsbDevicePermissionData>& data_set,
     }
 
     if (messages) {
-      messages->push_back(
-          PermissionMessage(PermissionMessage::kUsbDevice,
-                            l10n_util::GetStringUTF16(
-                                IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST),
-                            JoinString(details, base::char16('\n'))));
+      messages->push_back(PermissionMessage(
+          PermissionMessage::kUsbDevice,
+          l10n_util::GetStringUTF16(
+              IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST),
+          base::JoinString(details, base::ASCIIToUTF16("\n"))));
     }
     if (ids) {
       for (const auto& detail : details)
diff --git a/extensions/common/url_pattern.cc b/extensions/common/url_pattern.cc
index b72ce30..502c459 100644
--- a/extensions/common/url_pattern.cc
+++ b/extensions/common/url_pattern.cc
@@ -249,7 +249,7 @@ URLPattern::ParseResult URLPattern::Parse(const std::string& pattern) {
       host_components.erase(host_components.begin(),
                             host_components.begin() + 1);
     }
-    host_ = JoinString(host_components, '.');
+    host_ = base::JoinString(host_components, ".");
 
     path_start_pos = host_end_pos;
   }
diff --git a/extensions/renderer/print_native_handler.cc b/extensions/renderer/print_native_handler.cc
index 8e71eb5..b6ee63a 100644
--- a/extensions/renderer/print_native_handler.cc
+++ b/extensions/renderer/print_native_handler.cc
@@ -26,7 +26,7 @@ void PrintNativeHandler::Print(
   for (int i = 0; i < args.Length(); ++i)
     components.push_back(*v8::String::Utf8Value(args[i]));
 
-  LOG(ERROR) << JoinString(components, ',');
+  LOG(ERROR) << base::JoinString(components, ",");
 }
 
 }  // namespace extensions
diff --git a/gin/modules/console.cc b/gin/modules/console.cc
index 75241df..231d8fc 100644
--- a/gin/modules/console.cc
+++ b/gin/modules/console.cc
@@ -25,7 +25,7 @@ void Log(Arguments* args) {
     args->ThrowError();
     return;
   }
-  std::cout << JoinString(messages, ' ') << std::endl;
+  std::cout << base::JoinString(messages, " ") << std::endl;
 }
 
 WrapperInfo g_wrapper_info = { kEmbedderNativeGin };
diff --git a/google_apis/gaia/fake_gaia.cc b/google_apis/gaia/fake_gaia.cc
index bbf5216..7c73dd8 100644
--- a/google_apis/gaia/fake_gaia.cc
+++ b/google_apis/gaia/fake_gaia.cc
@@ -708,7 +708,7 @@ void FakeGaia::HandleTokenInfo(const HttpRequest& request,
     response_dict.SetString("user_id", token_info->user_id);
     std::vector<std::string> scope_vector(token_info->scopes.begin(),
                                           token_info->scopes.end());
-    response_dict.SetString("scope", JoinString(scope_vector, " "));
+    response_dict.SetString("scope", base::JoinString(scope_vector, " "));
     response_dict.SetInteger("expires_in", token_info->expires_in);
     response_dict.SetString("email", token_info->email);
     FormatJSONResponse(response_dict, http_response);
diff --git a/google_apis/gaia/gaia_auth_util.cc b/google_apis/gaia/gaia_auth_util.cc
index e9ec545..5464da6 100644
--- a/google_apis/gaia/gaia_auth_util.cc
+++ b/google_apis/gaia/gaia_auth_util.cc
@@ -36,7 +36,8 @@ std::string CanonicalizeEmailImpl(const std::string& email_address,
       base::RemoveChars(parts[0], ".", &parts[0]);
   }
 
-  std::string new_email = base::StringToLowerASCII(JoinString(parts, at));
+  std::string new_email = base::StringToLowerASCII(
+      base::JoinString(parts, "@"));
   VLOG(1) << "Canonicalized " << email_address << " to " << new_email;
   return new_email;
 }
diff --git a/google_apis/gaia/gaia_oauth_client.cc b/google_apis/gaia/gaia_oauth_client.cc
index 14c3cc3..c021623 100644
--- a/google_apis/gaia/gaia_oauth_client.cc
+++ b/google_apis/gaia/gaia_oauth_client.cc
@@ -137,7 +137,7 @@ void GaiaOAuthClient::Core::RefreshToken(
       "&grant_type=refresh_token";
 
   if (!scopes.empty()) {
-    std::string scopes_string = JoinString(scopes, ' ');
+    std::string scopes_string = base::JoinString(scopes, " ");
     post_body += "&scope=" + net::EscapeUrlEncodedData(scopes_string, true);
   }
 
diff --git a/google_apis/gaia/oauth2_access_token_fetcher_impl.cc b/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
index b513b78..1945c79 100644
--- a/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
+++ b/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
@@ -283,7 +283,7 @@ std::string OAuth2AccessTokenFetcherImpl::MakeGetAccessTokenBody(
                               enc_client_secret.c_str(),
                               enc_refresh_token.c_str());
   } else {
-    std::string scopes_string = JoinString(scopes, ' ');
+    std::string scopes_string = base::JoinString(scopes, " ");
     return base::StringPrintf(
         kGetAccessTokenBodyWithScopeFormat,
         enc_client_id.c_str(),
diff --git a/google_apis/gaia/oauth2_mint_token_flow.cc b/google_apis/gaia/oauth2_mint_token_flow.cc
index 0316c63..c2a6501 100644
--- a/google_apis/gaia/oauth2_mint_token_flow.cc
+++ b/google_apis/gaia/oauth2_mint_token_flow.cc
@@ -167,7 +167,7 @@ std::string OAuth2MintTokenFlow::CreateApiCallBody() {
       net::EscapeUrlEncodedData(force_value, true).c_str(),
       net::EscapeUrlEncodedData(response_type_value, true).c_str(),
       net::EscapeUrlEncodedData(
-          JoinString(parameters_.scopes, ' '), true).c_str(),
+          base::JoinString(parameters_.scopes, " "), true).c_str(),
       net::EscapeUrlEncodedData(parameters_.client_id, true).c_str(),
       net::EscapeUrlEncodedData(parameters_.extension_id, true).c_str());
   if (!parameters_.device_id.empty()) {
diff --git a/media/capture/capture_resolution_chooser.cc b/media/capture/capture_resolution_chooser.cc
index 768e129..d61fd76 100644
--- a/media/capture/capture_resolution_chooser.cc
+++ b/media/capture/capture_resolution_chooser.cc
@@ -231,7 +231,7 @@ void CaptureResolutionChooser::UpdateSnappedFrameSizes(
     for (const gfx::Size& size : snapped_sizes_)
       stringified_sizes.push_back(size.ToString());
     VLOG_STREAM(1) << "Recomputed snapped frame sizes: "
-                   << JoinString(stringified_sizes, " <--> ");
+                   << base::JoinString(stringified_sizes, " <--> ");
   }
 }
 
diff --git a/net/websockets/websocket_basic_handshake_stream.cc b/net/websockets/websocket_basic_handshake_stream.cc
index 616dbb1..a253e2e 100644
--- a/net/websockets/websocket_basic_handshake_stream.cc
+++ b/net/websockets/websocket_basic_handshake_stream.cc
@@ -99,7 +99,7 @@ void AddVectorHeaderIfNonEmpty(const char* name,
                                HttpRequestHeaders* headers) {
   if (value.empty())
     return;
-  headers->SetHeader(name, JoinString(value, ", "));
+  headers->SetHeader(name, base::JoinString(value, ", "));
 }
 
 GetHeaderResult GetSingleHeaderValue(const HttpResponseHeaders* headers,
@@ -346,7 +346,7 @@ bool ValidateExtensions(const HttpResponseHeaders* headers,
       }
     }
   }
-  *accepted_extensions_descriptor = JoinString(header_values, ", ");
+  *accepted_extensions_descriptor = base::JoinString(header_values, ", ");
   return true;
 }
 
diff --git a/remoting/base/capabilities.cc b/remoting/base/capabilities.cc
index 1226492..4903aed 100644
--- a/remoting/base/capabilities.cc
+++ b/remoting/base/capabilities.cc
@@ -36,7 +36,7 @@ std::string IntersectCapabilities(const std::string& client_capabilities,
       base::STLSetIntersection<std::vector<std::string> >(
           client_caps, host_caps);
 
-  return JoinString(result, " ");
+  return base::JoinString(result, " ");
 }
 
 }  // namespace remoting
diff --git a/remoting/base/capabilities_unittest.cc b/remoting/base/capabilities_unittest.cc
index 71dbd56..90c12a0 100644
--- a/remoting/base/capabilities_unittest.cc
+++ b/remoting/base/capabilities_unittest.cc
@@ -67,7 +67,7 @@ TEST(CapabilitiesTest, HasCapability) {
         base::SPLIT_WANT_NONEMPTY);
     do {
       EXPECT_EQ(data[i].result,
-                HasCapability(JoinString(caps, " "), data[i].key));
+                HasCapability(base::JoinString(caps, " "), data[i].key));
     } while (std::next_permutation(caps.begin(), caps.end()));
   }
 }
@@ -98,7 +98,8 @@ TEST(CapabilitiesTest, Intersect) {
         data[i].left, " ", base::KEEP_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
     do {
       EXPECT_EQ(data[i].result,
-                IntersectCapabilities(JoinString(caps, " "), data[i].right));
+                IntersectCapabilities(base::JoinString(caps, " "),
+                                      data[i].right));
     } while (std::next_permutation(caps.begin(), caps.end()));
   }
 }
diff --git a/sql/recovery.cc b/sql/recovery.cc
index f179a63..4308129 100644
--- a/sql/recovery.cc
+++ b/sql/recovery.cc
@@ -456,12 +456,12 @@ bool Recovery::AutoRecoverTable(const char* table_name,
       "CREATE VIRTUAL TABLE temp.recover_%s USING recover(corrupt.%s, %s)",
       table_name,
       table_name,
-      JoinString(create_column_decls, ',').c_str()));
+      base::JoinString(create_column_decls, ",").c_str()));
 
   std::string recover_insert(base::StringPrintf(
       "INSERT OR REPLACE INTO main.%s SELECT %s FROM temp.recover_%s",
       table_name,
-      JoinString(insert_columns, ',').c_str(),
+      base::JoinString(insert_columns, ",").c_str(),
       table_name));
 
   std::string recover_drop(base::StringPrintf(
diff --git a/tools/set_default_handler/set_default_handler_main.cc b/tools/set_default_handler/set_default_handler_main.cc
index 8b4b343..92edb6c 100644
--- a/tools/set_default_handler/set_default_handler_main.cc
+++ b/tools/set_default_handler/set_default_handler_main.cc
@@ -56,7 +56,7 @@ int wmain(int argc, wchar_t* argv[]) {
     printf("success\n");
   } else if (!choices.empty()) {
     printf("failed to set program. possible choices: %ls\n",
-           JoinString(choices, L", ").c_str());
+           base::JoinString(choices, L", ").c_str());
   } else {
     printf("failed with HRESULT: %0x08X\n", result);
   }
diff --git a/ui/app_list/search/history.cc b/ui/app_list/search/history.cc
index 6c54024..7d38bb2 100644
--- a/ui/app_list/search/history.cc
+++ b/ui/app_list/search/history.cc
@@ -17,7 +17,8 @@ namespace {
 // Normalize the given string by joining all its tokens with a space.
 std::string NormalizeString(const std::string& utf8) {
   TokenizedString tokenized(base::UTF8ToUTF16(utf8));
-  return base::UTF16ToUTF8(JoinString(tokenized.tokens(), ' '));
+  return base::UTF16ToUTF8(
+      base::JoinString(tokenized.tokens(), base::ASCIIToUTF16(" ")));
 }
 
 }  // namespace
diff --git a/ui/app_list/search/tokenized_string_char_iterator_unittest.cc b/ui/app_list/search/tokenized_string_char_iterator_unittest.cc
index 3846014..d5fe1b3 100644
--- a/ui/app_list/search/tokenized_string_char_iterator_unittest.cc
+++ b/ui/app_list/search/tokenized_string_char_iterator_unittest.cc
@@ -48,7 +48,7 @@ void TestEveryChar(const std::string& text, const std::string& expects) {
     iter.NextChar();
   }
 
-  EXPECT_EQ(expects, JoinString(results, ' '));
+  EXPECT_EQ(expects, base::JoinString(results, " "));
   TestBeyondTheEnd(&iter);
 }
 
@@ -62,7 +62,7 @@ void TestNextToken(const std::string& text, const std::string& expects) {
     iter.NextToken();
   }
 
-  EXPECT_EQ(expects, JoinString(results, ' '));
+  EXPECT_EQ(expects, base::JoinString(results, " "));
   TestBeyondTheEnd(&iter);
 }
 
@@ -80,7 +80,7 @@ void TestFirstTwoCharInEveryToken(const std::string& text,
     iter.NextToken();
   }
 
-  EXPECT_EQ(expects, JoinString(results, ' '));
+  EXPECT_EQ(expects, base::JoinString(results, " "));
   TestBeyondTheEnd(&iter);
 }
 
diff --git a/ui/base/dragdrop/os_exchange_data_provider_aurax11.cc b/ui/base/dragdrop/os_exchange_data_provider_aurax11.cc
index e7a815c4..73ec4bf 100644
--- a/ui/base/dragdrop/os_exchange_data_provider_aurax11.cc
+++ b/ui/base/dragdrop/os_exchange_data_provider_aurax11.cc
@@ -199,7 +199,7 @@ void OSExchangeDataProviderAuraX11::SetFilenames(
       paths.push_back(url_spec);
   }
 
-  std::string joined_data = JoinString(paths, '\n');
+  std::string joined_data = base::JoinString(paths, "\n");
   scoped_refptr<base::RefCountedMemory> mem(
       base::RefCountedString::TakeString(&joined_data));
   format_map_.Insert(atom_cache_.GetAtom(Clipboard::kMimeTypeURIList), mem);
diff --git a/ui/gfx/font_list_impl.cc b/ui/gfx/font_list_impl.cc
index 4037032..907f4ef 100644
--- a/ui/gfx/font_list_impl.cc
+++ b/ui/gfx/font_list_impl.cc
@@ -18,7 +18,7 @@ namespace {
 std::string BuildDescription(const std::vector<std::string>& families,
                              int style,
                              int size_pixels) {
-  std::string description = JoinString(families, ',');
+  std::string description = base::JoinString(families, ",");
   description += ",";
 
   if (style & gfx::Font::BOLD)
diff --git a/ui/gfx/font_render_params_linux.cc b/ui/gfx/font_render_params_linux.cc
index f09f703..b62c525 100644
--- a/ui/gfx/font_render_params_linux.cc
+++ b/ui/gfx/font_render_params_linux.cc
@@ -192,7 +192,8 @@ bool QueryFontconfig(const FontRenderParamsQuery& query,
 uint32 HashFontRenderParamsQuery(const FontRenderParamsQuery& query) {
   return base::Hash(base::StringPrintf(
       "%d|%d|%d|%s|%f", query.pixel_size, query.point_size, query.style,
-      JoinString(query.families, ',').c_str(), query.device_scale_factor));
+      base::JoinString(query.families, ",").c_str(),
+      query.device_scale_factor));
 }
 
 }  // namespace
diff --git a/ui/gfx/text_elider_unittest.cc b/ui/gfx/text_elider_unittest.cc
index 5eeea5c..b0baa42 100644
--- a/ui/gfx/text_elider_unittest.cc
+++ b/ui/gfx/text_elider_unittest.cc
@@ -668,7 +668,8 @@ TEST(TextEliderTest, MAYBE_ElideRectangleText) {
                                  TRUNCATE_LONG_WORDS,
                                  &lines));
     if (cases[i].output) {
-      const std::string result = UTF16ToUTF8(JoinString(lines, '|'));
+      const std::string result =
+          UTF16ToUTF8(base::JoinString(lines, ASCIIToUTF16("|")));
       EXPECT_EQ(cases[i].output, result) << "Case " << i << " failed!";
     } else {
       EXPECT_TRUE(lines.empty()) << "Case " << i << " failed!";
@@ -715,7 +716,8 @@ TEST(TextEliderTest, MAYBE_ElideRectangleTextPunctuation) {
                                  wrap_behavior,
                                  &lines));
     if (cases[i].output) {
-      const std::string result = UTF16ToUTF8(JoinString(lines, '|'));
+      const std::string result =
+          UTF16ToUTF8(base::JoinString(lines, base::ASCIIToUTF16("|")));
       EXPECT_EQ(cases[i].output, result) << "Case " << i << " failed!";
     } else {
       EXPECT_TRUE(lines.empty()) << "Case " << i << " failed!";
@@ -784,7 +786,8 @@ TEST(TextEliderTest, MAYBE_ElideRectangleTextLongWords) {
                                  &lines));
     std::string expected_output(cases[i].output);
     base::ReplaceSubstringsAfterOffset(&expected_output, 0, "...", kEllipsis);
-    const std::string result = UTF16ToUTF8(JoinString(lines, '|'));
+    const std::string result =
+        UTF16ToUTF8(base::JoinString(lines, base::ASCIIToUTF16("|")));
     EXPECT_EQ(expected_output, result) << "Case " << i << " failed!";
   }
 }
diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index 1049bfd..2098411 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -100,7 +100,7 @@ std::string GLContext::GetExtensions() {
     DCHECK(extension != nullptr);
     exts.push_back(extension);
   }
-  return JoinString(exts, " ");
+  return base::JoinString(exts, " ");
 }
 
 std::string GLContext::GetGLVersion() {
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index 1d6fcb1..76af744 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -492,7 +492,7 @@ void RealGLApi::InitializeFilteredExtensions() {
     }
 
     // Construct filtered extensions string for GL_EXTENSIONS string lookups.
-    filtered_exts_str_ = JoinString(filtered_exts_, " ");
+    filtered_exts_str_ = base::JoinString(filtered_exts_, " ");
   }
 }
 
@@ -530,7 +530,7 @@ void VirtualGLApi::Initialize(DriverGL* driver, GLContext* real_context) {
   if (it != ext.end())
     ext.erase(it);
 
-  extensions_ = JoinString(ext, " ");
+  extensions_ = base::JoinString(ext, " ");
 }
 
 bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
diff --git a/ui/gl/gl_implementation.cc b/ui/gl/gl_implementation.cc
index 4fae0ec..96921bc 100644
--- a/ui/gl/gl_implementation.cc
+++ b/ui/gl/gl_implementation.cc
@@ -173,7 +173,7 @@ std::string FilterGLExtensionList(
       std::remove_if(extension_vec.begin(), extension_vec.end(), is_disabled),
       extension_vec.end());
 
-  return JoinString(extension_vec, " ");
+  return base::JoinString(extension_vec, " ");
 }
 
 DisableNullDrawGLBindings::DisableNullDrawGLBindings() {
diff --git a/ui/message_center/cocoa/notification_controller.mm b/ui/message_center/cocoa/notification_controller.mm
index f9266a2..1b4e96a 100644
--- a/ui/message_center/cocoa/notification_controller.mm
+++ b/ui/message_center/cocoa/notification_controller.mm
@@ -883,7 +883,8 @@
   }
 
   *actualLines = wrapped.size();
-  return lines == 1 ? wrapped[0] : JoinString(wrapped, '\n');
+  return lines == 1 ? wrapped[0]
+                    : base::JoinString(wrapped, base::ASCIIToUTF16("\n"));
 }
 
 - (base::string16)wrapText:(const base::string16&)text
diff --git a/ui/message_center/views/bounded_label.cc b/ui/message_center/views/bounded_label.cc
index 5bf6f15..f9f6ffb 100644
--- a/ui/message_center/views/bounded_label.cc
+++ b/ui/message_center/views/bounded_label.cc
@@ -113,10 +113,10 @@ gfx::Size InnerBoundedLabel::GetSizeForWidthAndLines(int width, int lines) {
                                    std::max(width - insets.width(), 0);
     int text_height = std::numeric_limits<int>::max();
     std::vector<base::string16> wrapped = GetWrappedText(text_width, lines);
-    gfx::Canvas::SizeStringInt(JoinString(wrapped, '\n'), font_list(),
-                               &text_width, &text_height,
-                               owner_->GetLineHeight(),
-                               GetTextFlags());
+    gfx::Canvas::SizeStringInt(
+        base::JoinString(wrapped, base::ASCIIToUTF16("\n")),
+        font_list(), &text_width, &text_height, owner_->GetLineHeight(),
+        GetTextFlags());
     size.set_width(text_width + insets.width());
     size.set_height(text_height + insets.height());
     SetCachedSize(key, size);
@@ -177,7 +177,8 @@ void InnerBoundedLabel::OnPaint(gfx::Canvas* canvas) {
     gfx::Rect bounds(width(), height);
     bounds.Inset(owner_->GetInsets());
     if (bounds.width() != wrapped_text_width_ || lines != wrapped_text_lines_) {
-      wrapped_text_ = JoinString(GetWrappedText(bounds.width(), lines), '\n');
+      wrapped_text_ = base::JoinString(GetWrappedText(bounds.width(), lines),
+                                       base::ASCIIToUTF16("\n"));
       wrapped_text_width_ = bounds.width();
       wrapped_text_lines_ = lines;
     }
@@ -343,7 +344,8 @@ void BoundedLabel::OnNativeThemeChanged(const ui::NativeTheme* theme) {
 }
 
 base::string16 BoundedLabel::GetWrappedTextForTest(int width, int lines) {
-  return JoinString(label_->GetWrappedText(width, lines), '\n');
+  return base::JoinString(label_->GetWrappedText(width, lines),
+                          base::ASCIIToUTF16("\n"));
 }
 
 }  // namespace message_center
diff --git a/ui/message_center/views/notification_view.cc b/ui/message_center/views/notification_view.cc
index 5f314b5..e9294f8 100644
--- a/ui/message_center/views/notification_view.cc
+++ b/ui/message_center/views/notification_view.cc
@@ -334,7 +334,8 @@ void NotificationView::SetAccessibleName(const Notification& notification) {
     accessible_lines.push_back(items[i].title + base::ASCIIToUTF16(" ") +
                                items[i].message);
   }
-  set_accessible_name(JoinString(accessible_lines, '\n'));
+  set_accessible_name(
+      base::JoinString(accessible_lines, base::ASCIIToUTF16("\n")));
 }
 
 NotificationView::NotificationView(MessageCenterController* controller,
diff --git a/ui/views/controls/table/table_view.cc b/ui/views/controls/table/table_view.cc
index 8104a96..6c37e52 100644
--- a/ui/views/controls/table/table_view.cc
+++ b/ui/views/controls/table/table_view.cc
@@ -448,7 +448,7 @@ void TableView::GetAccessibleState(ui::AXViewState* state) {
         name_parts.push_back(value);
       }
     }
-    state->name = JoinString(name_parts, base::ASCIIToUTF16(", "));
+    state->name = base::JoinString(name_parts, base::ASCIIToUTF16(", "));
   }
 }