Add module for counting date-last-roll-call and persisting those counts

components/update_client/configurator.h

Index: components/update_client/configurator.h
diff --git a/components/update_client/configurator.h b/components/update_client/configurator.h
index 177c4a7771b19a5142da98b2411be356e7cc902c..874241536eee91f742f268b2c932bd435fb5eb80 100644
--- a/components/update_client/configurator.h
+++ b/components/update_client/configurator.h
@@ -12,6 +12,7 @@
 #include "base/memory/scoped_ptr.h"
 
 class GURL;
+class PrefService;
 
 namespace base {
 class SequencedTaskRunner;
@@ -111,6 +112,14 @@ class Configurator : public base::RefCountedThreadSafe<Configurator> {
   virtual scoped_refptr<base::SequencedTaskRunner> GetSequencedTaskRunner()
       const = 0;
 
+  // Returns a PrefService that the update_client can use to store persistent
+  // update information. The PrefService must outlive the entire update_client,
+  // and be safe to access from the thread the update_client is constructed
+  // on.
+  // Returning NULL is safe and will disable any functionality that requires

[Bernhard Bauer, 2016/04/08 09:06:09]

Nit: Now that the NULL #define is deprecated, I would use "null" for the
conceptual null value (which we implement in code with `nullptr`).

[waffles, 2016/04/08 19:11:00]

Done.

+  // persistent storage.
+  virtual PrefService* GetPrefService() const = 0;
+
  protected:
   friend class base::RefCountedThreadSafe<Configurator>;