Give access to a network time kept in the variation service.

chrome/browser/metrics/variations/variations_service.h

Index: chrome/browser/metrics/variations/variations_service.h
diff --git a/chrome/browser/metrics/variations/variations_service.h b/chrome/browser/metrics/variations/variations_service.h
index cd5bd36cd199912fb0d43d478409f9cfcbdb2cd2..7f067eaae89d226746cc9616e003f83f91a94509 100644
--- a/chrome/browser/metrics/variations/variations_service.h
+++ b/chrome/browser/metrics/variations/variations_service.h
@@ -47,6 +47,10 @@ class VariationsService
   // |CreateTrialsFromSeed|.
   void StartRepeatedVariationsSeedFetch();
 
+  // TODO(mad): Remove this once NetworkTimeService is extracted as stand alone.
+  bool GetNetworkTime(base::Time* network_time,
+                      base::TimeDelta* uncertainty) const;
+
 #if defined(OS_WIN)
   // Starts syncing Google Update Variation IDs with the registry.
   void StartGoogleUpdateRegistrySync();
@@ -183,6 +187,36 @@ class VariationsService
   // latency of seed requests. Initially zero.
   base::TimeTicks last_request_started_time_;
 
+  // TODO(mad): Eventually move this to a NetworkTimeService.
+  class NetworkTimeService {

[Alexei Svitkine (slow), 2013/02/01 22:18:08]

Put it in a separate file. "Service" is too ambitious a name for this, for now.

How about NetworkTimeTracker?

You can put the separate file in the same directory as VariationsService with a
TODO comment explaining the eventual plan.

[MAD, 2013/02/04 21:07:43]

Done.

+   public:
+    NetworkTimeService() {

[Alexei Svitkine (slow), 2013/02/01 22:18:08]

When this is a file, add a dtor and don't inline their impls.

[MAD, 2013/02/04 21:07:43]

Done.

+    };
+
+    // Returns a network time based on previous url request header value and CPU
+    // ticks count since then. Returns false if no network time is available
+    // yet. Can also return the error range if |uncertainty| isn't NULL.
+    bool GetNetworkTime(base::Time* network_time,
+                        base::TimeDelta* uncertainty) const;
+   private:
+    // TODO(mad): Remove this once NetworkTimeService is extracted from here.
+    friend class VariationsService;

[Alexei Svitkine (slow), 2013/02/01 22:18:08]

Remove this and change the SetNetworkTime() call to UpdateNetworkTime(). You can
make it public, since only VariationsService has access to the instance.

[MAD, 2013/02/04 21:07:43]

Done.

+
+    void SetNetworkTime(const base::Time& network_time,
+                        const base::TimeDelta& latency);
+
+    // Remember the network time based on last url request header value.
+    base::Time network_time_;
+
+    // The estimated ticks count when the date was set on the url request.
+    base::TimeTicks network_time_ticks_;
+
+    // Uncertainty of time based on added inaccuracies of the time is acquired.
+    base::TimeDelta network_time_uncertainty_;
+
+    DISALLOW_COPY_AND_ASSIGN(NetworkTimeService);
+  } network_service_;
+
 #if defined(OS_WIN)
   // Helper that handles synchronizing Variations with the Registry.
   VariationsRegistrySyncer registry_syncer_;