update_engine: Add minutes variable to real time provider.

Make it so that the user can also get the current
minutes in local time from the real time provider.

BUG=chromium:852860
TEST=Real time provider unittests
Change-Id: I8118e28c5ab7f000434947fdee9aeae441535ba6
Reviewed-on: https://chromium-review.googlesource.com/1101468
Commit-Ready: Adolfo Higueros <adokar@google.com>
Tested-by: Adolfo Higueros <adokar@google.com>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/update_manager/real_time_provider.h b/update_manager/real_time_provider.h
index e7cae94..989cefb 100644
--- a/update_manager/real_time_provider.h
+++ b/update_manager/real_time_provider.h
@@ -43,12 +43,15 @@
     return var_curr_hour_.get();
   }
 
+  Variable<int>* var_curr_minute() override { return var_curr_minute_.get(); }
+
  private:
   // A clock abstraction (fakeable).
   chromeos_update_engine::ClockInterface* const clock_;
 
   std::unique_ptr<Variable<base::Time>> var_curr_date_;
   std::unique_ptr<Variable<int>> var_curr_hour_;
+  std::unique_ptr<Variable<int>> var_curr_minute_;
 
   DISALLOW_COPY_AND_ASSIGN(RealTimeProvider);
 };