Rewrite std::string("") to std::string(), Linux edition.

chrome/test/webdriver/webdriver_key_converter.cc

Index: chrome/test/webdriver/webdriver_key_converter.cc
diff --git a/chrome/test/webdriver/webdriver_key_converter.cc b/chrome/test/webdriver/webdriver_key_converter.cc
index e19e9dc73ac8846aaaffa3968d791b3eae6ac9a2..b83d3cb75b36340a8d43ce3a8d32a2609f173ff9 100644
--- a/chrome/test/webdriver/webdriver_key_converter.cc
+++ b/chrome/test/webdriver/webdriver_key_converter.cc
@@ -162,11 +162,19 @@ bool KeyCodeFromShorthandKey(char16 key_utf16,
 namespace webdriver {
 
 WebKeyEvent CreateKeyDownEvent(ui::KeyboardCode key_code, int modifiers) {
-  return WebKeyEvent(automation::kRawKeyDownType, key_code, "", "", modifiers);
+  return WebKeyEvent(automation::kRawKeyDownType,
+                     key_code,
+                     std::string(),
+                     std::string(),
+                     modifiers);
 }
 
 WebKeyEvent CreateKeyUpEvent(ui::KeyboardCode key_code, int modifiers) {
-  return WebKeyEvent(automation::kKeyUpType, key_code, "", "", modifiers);
+  return WebKeyEvent(automation::kKeyUpType,
+                     key_code,
+                     std::string(),
+                     std::string(),
+                     modifiers);
 }
 
 WebKeyEvent CreateCharEvent(const std::string& unmodified_text,