Allow TranslateRanker to override decisions taken by heuristics.

components/translate/core/browser/translate_accept_languages.h

 // 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.
 
 #ifndef COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_ACCEPT_LANGUAGES_H_
 #define COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_ACCEPT_LANGUAGES_H_
 
 #include <set>
 #include <string>
 
@@ skipping 16 matching lines @@
 
   // Returns true if |language| is available as Accept-Languages. |language|
   // will be converted if it has the synonym of accept language.
   static bool CanBeAcceptLanguage(const std::string& language);
 
   // Returns true if the passed language has been configured by the user as an
   // accept language. |language| will be converted if it has the synonym of
   // accept languages.
   bool IsAcceptLanguage(const std::string& language);
 
+ protected:
+  // Default constructor. Used for creating mocks in tests.
+  TranslateAcceptLanguages();

[groby-ooo-7-16, 2017/04/10 20:52:47]

I don't think that's necessary - see e.g MockTranslateClient

Or just set the acceptlanguage prefs?

[hamelphi, 2017/04/11 22:46:07]

Since TranslateAcceptLanguages has a non-default constructor, it needs to be
called by GMock, as far as I understand.
I tried to call the true constructor with the PrefService, but this crashes with
a segfault. 
#3 0x7f1281e7855d PrefService::GetString()
#4 0x0000044d741f translate::TranslateAcceptLanguages::InitAcceptLanguages()

I tried a bunch of ways, but could not figure out a way to correctly initialize
the TranslateAcceptLangues object. I am quite confused about what is what here.
For TranslateManager unittests, we should not require the logic from
TranslateAcceptLanguages anyway. I think that logic should be tested elsewhere.
Having this protected default constructor allows us to bypass the problematic
initialization.

[hamelphi, 2017/04/12 21:10:53]

This is not necessary anymore, since I do not call InitiateTranslation in my
unitttests.

[groby-ooo-7-16, 2017/04/20 19:45:57]

Just FYI: It crashes on GetString because the property is not registered, I
think. Any test using TranslatePrefs must register a few properties (see
existing tests)

+
  private:
   // Initializes the |accept_languages_| language table based on the associated
   // preference in |prefs|.
   void InitAcceptLanguages(PrefService* prefs);
 
   // Set of accept languages.
   std::set<std::string> accept_languages_;
 
   // Listens to accept languages changes.
   PrefChangeRegistrar pref_change_registrar_;
 
   // Path of accept languages preference.
   const std::string accept_languages_pref_;
 
   DISALLOW_COPY_AND_ASSIGN(TranslateAcceptLanguages);
 };
 
 }  // namespace translate
 
 #endif  // COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_ACCEPT_LANGUAGES_H_