Build third-party code with -Wall, build chromium_code with -Wextra on Linux

chrome/browser/chromeos/extensions/accessibility_features_apitest.cc

 // Copyright 2014 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 <stddef.h>
 
 #include <string>
 #include <vector>
 
 #include "base/json/json_writer.h"
@@ skipping 51 matching lines @@
     if (GetParam())
       return kTestExtensionPathMofifyPermission;
     return kTestExtensionPathReadPermission;
   }
 
   // Whether a parameterized test should have been able to modify accessibility
   // preferences (i.e. whether the test extension had modify permission).
   bool ShouldModifyingFeatureSucceed() const { return GetParam(); }
 
   // Returns preference path for accessibility features as defined by the API.
-  const char* const GetPrefForFeature(const std::string& feature) {
+  const char* GetPrefForFeature(const std::string& feature) {
     if (feature == "spokenFeedback")
       return prefs::kAccessibilitySpokenFeedbackEnabled;
     if (feature == "largeCursor")
       return prefs::kAccessibilityLargeCursorEnabled;
     if (feature == "stickyKeys")
       return prefs::kAccessibilityStickyKeysEnabled;
     if (feature == "highContrast")
       return prefs::kAccessibilityHighContrastEnabled;
     if (feature == "screenMagnifier")
       return prefs::kAccessibilityScreenMagnifierEnabled;
@@ skipping 187 matching lines @@
       InitPrefServiceForTest(GetPrefs(), disabled_features, enabled_features));
 
   // Catch the second result notification sent by the test extension.
   ResultCatcher result_catcher;
   ASSERT_TRUE(result_catcher.GetNextResult()) << result_catcher.message();
 }
 
 }  // namespace
 
 }  // namespace extensions