Add updater state for Mac.

components/update_client/updater_state.h

Index: components/update_client/updater_state.h
diff --git a/components/update_client/updater_state.h b/components/update_client/updater_state.h
index cd537eca589e78f193b72cff37c995ca75957d65..f5cdf553a8d2d963b1b76f8c8b2eb714121e471b 100644
--- a/components/update_client/updater_state.h
+++ b/components/update_client/updater_state.h
@@ -47,8 +47,12 @@ class UpdaterState {
   static bool IsJoinedToDomain();
   static base::Time GetUpdaterLastStartedAU(bool is_machine);
   static base::Time GetUpdaterLastChecked(bool is_machine);
+#if defined(OS_WIN)

[Sorin Jianu, 2017/05/04 19:53:58]

can we avoid conditional compilation in this file? Can we ignore the is_machine
parameter on macOS?

[borisv, 2017/05/04 22:19:27]

We have to user conditional anyway anyway for the  wchar_t* and char*
difference. I don't believe that Mac knows wchar_t at all. Alternatively, we can
drag an additional header to define it as base::FilePath::CharType. Or we can
try forward declaration of base::FilePath::CharType and then include that header
in updater_state_win.cc. 

A third option (my preference) is that we pull this method out of the class
definition at all. As this is a static method, it can very well be defined
locally for the _win and _mac implementation files. 

[Sorin Jianu, 2017/05/04 22:50:48]

wchar_t is a standard type.

Also, I can change the code to take a char literal, if that is better
accommodated, please tell me which one would you prefer.

   static base::Time GetUpdaterTimeValue(bool is_machine,
                                         const wchar_t* value_name);
+#else
+  static base::Time GetUpdaterTimeValue(const char* value_name);
+#endif
   static int GetUpdatePolicy();
 
   static std::string NormalizeTimeDelta(const base::TimeDelta& delta);