Pref service strings should be std::string.

Part 1: Convert RegisterStringPref.

BUG=none
TEST=compile

Review URL: http://codereview.chromium.org/2809022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@50202 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/pref_service_unittest.cc b/chrome/browser/pref_service_unittest.cc
index 49ac729..fe97b134 100644
--- a/chrome/browser/pref_service_unittest.cc
+++ b/chrome/browser/pref_service_unittest.cc
@@ -89,7 +89,7 @@
   PrefService prefs(new PrefValueStore(NULL, new DummyPrefStore(), NULL));
 
   const wchar_t pref_name[] = L"homepage";
-  prefs.RegisterStringPref(pref_name, L"");
+  prefs.RegisterStringPref(pref_name, "");
 
   const std::wstring new_pref_value(L"http://www.google.com/");
   TestPrefObserver obs(&prefs, pref_name, new_pref_value);
@@ -130,7 +130,7 @@
 
   // Register the path. This doesn't set a value, so the path still shouldn't
   // exist.
-  prefs.RegisterStringPref(path, std::wstring());
+  prefs.RegisterStringPref(path, std::string());
   EXPECT_FALSE(prefs.HasPrefPath(path));
 
   // Set a value and make sure we have a path.
@@ -146,7 +146,7 @@
   DummyPrefStore* pref_store = new DummyPrefStore();
   pref_store->set_prefs(dict);
   PrefService prefs(new PrefValueStore(NULL, pref_store, NULL));
-  prefs.RegisterStringPref(pref_name, L"");
+  prefs.RegisterStringPref(pref_name, "");
 
   const std::wstring new_pref_value(L"http://www.google.com/");
   TestPrefObserver obs(&prefs, pref_name, new_pref_value);
@@ -210,7 +210,7 @@
 const wchar_t PrefServiceSetValueTest::value_[] = L"value";
 
 TEST_F(PrefServiceSetValueTest, SetStringValue) {
-  const wchar_t default_string[] = L"default";
+  const char default_string[] = "default";
   scoped_ptr<Value> default_value(Value::CreateStringValue(default_string));
   prefs_.RegisterStringPref(name_, default_string);
   prefs_.AddPrefObserver(name_, &observer_);