[NTP Snippets] Another round of clang-tidy cleanups

components/translate/core/browser/language_model.h

 // Copyright 2016 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.
 
 #ifndef COMPONENTS_TRANSLATE_CORE_BROWSER_LANGUAGE_MODEL_H_
 #define COMPONENTS_TRANSLATE_CORE_BROWSER_LANGUAGE_MODEL_H_
 
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "components/keyed_service/core/keyed_service.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace translate {
 
 // Collects data about languages in which the user reads the web and provides
 // access to current estimated language preferences. The past behaviour is
 // discounted so that this model reflects changes in browsing habits. This model
 // does not have to contain all languages that ever appeared in user's browsing,
 // languages with insignificant frequency are removed, eventually.
 class LanguageModel : public KeyedService {
  public:
   struct LanguageInfo {
+    LanguageInfo() = default;

[Bernhard Bauer, 2016/10/26 09:24:02]

So, is there a rule for when to use {} and when to use = default? Seems like
this would work with {} as well, no?

[Marc Treib, 2016/10/26 09:29:40]

I don't know of any "official" rule - my personal one is to prefer "= default"
when possible. In the ctor below, it isn't - you can't have both an initializer
list and "= default".

+    LanguageInfo(const std::string& language_code, float frequency)
+        : language_code(language_code), frequency(frequency) {}
+
     // The ISO 639 language code.
     std::string language_code;
 
     // The current estimated frequency of the language share, a number between 0
     // and 1 (can be understood as the probability that the next page the user
     // opens is in this language). Frequencies over all LanguageInfos from
     // GetTopLanguages() sum to 1 (unless there are no top languages, yet).
-    float frequency;
+    float frequency = 0.0f;

[Marc Treib, 2016/10/26 09:21:05]

Uninitialized values are Teh Evilz! :)
Unfortunately, adding this breaks c-style initialization for some reason, hence
the constructor above and the change in the .cc file.

 
     bool operator==(const LanguageInfo& m) const {
       return language_code == m.language_code;
     }
   };
 
   explicit LanguageModel(PrefService* pref_service);
   ~LanguageModel() override;
 
   // Registers profile prefs for the model.
@@ skipping 13 matching lines @@
 
  private:
   PrefService* pref_service_;
 
   DISALLOW_COPY_AND_ASSIGN(LanguageModel);
 };
 
 }  // namespace translate
 
 #endif  // COMPONENTS_TRANSLATE_CORE_BROWSER_LANGUAGE_MODEL_H_