Update from https://crrev.com/311076

base/test/expectations/expectation.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/test/expectations/expectation.h"
 
 #include "base/logging.h"
 
 #if defined(OS_WIN)
 #include "base/win/windows_version.h"
@@ skipping 20 matching lines @@
     return false;
 
   return true;
 }
 
 static bool IsValidPlatform(const Platform* platform) {
   const std::string& name = platform->name;
   const std::string& variant = platform->variant;
 
   if (name == "Win") {
-    if (variant != "" &&
+    if (!variant.empty() &&
         variant != "XP" &&
         variant != "Vista" &&
         variant != "7" &&
         variant != "8") {
       return false;
     }
   } else if (name == "Mac") {
-    if (variant != "" &&
+    if (!variant.empty() &&
         variant != "10.6" &&
         variant != "10.7" &&
         variant != "10.8" &&
         variant != "10.9" &&
         variant != "10.10") {
       return false;
     }
   } else if (name == "Linux") {
-    if (variant != "" &&
+    if (!variant.empty() &&
         variant != "32" &&
         variant != "64") {
       return false;
     }
   } else if (name == "ChromeOS") {
     // TODO(rsesek): Figure out what ChromeOS needs.
   } else if (name == "iOS") {
     // TODO(rsesek): Figure out what iOS needs. Probably Device and Simulator.
   } else if (name == "Android") {
     // TODO(rsesek): Figure out what Android needs.
@@ skipping 83 matching lines @@
 }
 
 Expectation::Expectation()
     : configuration(CONFIGURATION_UNSPECIFIED),
       result(RESULT_PASS) {
 }
 
 Expectation::~Expectation() {}
 
 }  // namespace test_expectations