Add a mechanism for collecting Rappor samples on a daily interval.

components/rappor/rappor_service.h

Index: components/rappor/rappor_service.h
diff --git a/components/rappor/rappor_service.h b/components/rappor/rappor_service.h
index f02a85a3fe65e48d13738531627496c854a78b18..03177a3d9284178a0d4fc1d4ee6a7f1b5045742b 100644
--- a/components/rappor/rappor_service.h
+++ b/components/rappor/rappor_service.h
@@ -12,6 +12,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer/timer.h"
+#include "components/metrics/daily_interval.h"
 
 class PrefRegistrySimple;
 class PrefService;
@@ -38,12 +39,17 @@ enum RapporType {
 // and periodically generates and uploads reports based on the collected data.
 class RapporService {
  public:
-  RapporService();
+  // Constructs a RapporService.
+  // Calling code is responsible for ensuring that the lifetime of
+  // |pref_service| is longer than the lifetime of RapporService.
+  RapporService(PrefService* pref_service);
   virtual ~RapporService();
 
+  // Add an observer for collecting daily metrics.
+  void AddDailyMetric(metrics::DailyObserver* observer);
+
   // Starts the periodic generation of reports and upload attempts.
-  void Start(PrefService* pref_service,
-             net::URLRequestContextGetter* context,
+  void Start(net::URLRequestContextGetter* context,
              bool metrics_enabled);
 
   // Records a sample of the rappor metric specified by |metric_name|.
@@ -63,6 +69,15 @@ class RapporService {
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
  protected:
+  // Retrieves the cohort number this client was assigned to, generating it if
+  // doesn't already exist.  The cohort should be persistent.
+  void LoadCohort();
+
+  // Retrieves the value for secret_ from preferences, generating it if doesn't
+  // already exist.  The secret should be persistent, so that additional bits
+  // from the client do not get exposed over time.
+  void LoadSecret();
+
   // Logs all of the collected metrics to the reports proto message and clears
   // the internal map.  Exposed for tests.  Returns true if any metrics were
   // recorded.
@@ -79,15 +94,6 @@ class RapporService {
   // Check if the service has been started successfully.
   bool IsInitialized() const;
 
-  // Retrieves the cohort number this client was assigned to, generating it if
-  // doesn't already exist.  The cohort should be persistent.
-  void LoadCohort(PrefService* pref_service);
-
-  // Retrieves the value for secret_ from preferences, generating it if doesn't
-  // already exist.  The secret should be persistent, so that additional bits
-  // from the client do not get exposed over time.
-  void LoadSecret(PrefService* pref_service);
-
   // Called whenever the logging interval elapses to generate a new log of
   // reports and pass it to the uploader.
   void OnLogInterval();
@@ -97,6 +103,11 @@ class RapporService {
   RapporMetric* LookUpMetric(const std::string& metric_name,
                              const RapporParameters& parameters);
 
+  // A weak pointer to the PrefService object to read and write preferences
+  // from.  Calling code should ensure this object continues to exist for the
+  // lifetime of the DailyInterval object.
+  PrefService* pref_service_;
+
   // Client-side secret used to generate fake bits.
   std::string secret_;
 
@@ -106,6 +117,9 @@ class RapporService {
   // Timer which schedules calls to OnLogInterval().
   base::OneShotTimer<RapporService> log_rotation_timer_;
 
+  // A daily interval tracker.
+  metrics::DailyInterval daily_interval_;
+
   // A private LogUploader instance for sending reports to the server.
   scoped_ptr<LogUploader> uploader_;