Expose API to store and load data usage stats from UI task runner.

components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h
index 0ed7d1b386c3d349b91409ca857c29068d290f5c..3698dd9eed1056a0e2f9e6ff8c01abd4357e4ac0 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.h
@@ -26,6 +26,7 @@ class Value;
 }
 
 namespace data_reduction_proxy {
+class DataReductionProxyService;
 
 // Data reduction proxy delayed pref service reduces the number calls to pref
 // service by storing prefs in memory and writing to the given PrefService after
@@ -34,15 +35,19 @@ namespace data_reduction_proxy {
 // prefs must be stored and read on the UI thread.
 class DataReductionProxyCompressionStats {
  public:
-  // Constructs a data reduction proxy delayed pref service object using
-  // |pref_service|. Writes prefs to |pref_service| after |delay|
-  // and stores them in |pref_map_| and |list_pref_map| between writes.
+  // Collects and store data usage and compression statistics. Basic data usage
+  // stats are stored in browser preferences. More detailed stats broken down
+  // by site and internet type are stored in |DataReductionProxyStore|.
+  //
+  // To store basic stats, it constructs a data reduction proxy delayed pref
+  // service object using |pref_service|. Writes prefs to |pref_service| after
+  // |delay| and stores them in |pref_map_| and |list_pref_map| between writes.
   // If |delay| is zero, writes directly to the PrefService and does not store
   // in the maps.
   DataReductionProxyCompressionStats(
       PrefService* pref_service,
-      scoped_refptr<base::SequencedTaskRunner> task_runner,
-      const base::TimeDelta& delay);
+      const scoped_refptr<base::SequencedTaskRunner>& task_runner,
+      base::TimeDelta delay);
   ~DataReductionProxyCompressionStats();
 
   // Records daily data savings statistics to prefs and reports data savings
@@ -77,6 +82,11 @@ class DataReductionProxyCompressionStats {
                          int64* received_content_length,
                          int64* last_update_time);
 
+  // Sets the |DataReductionProxyService|.
+  void set_data_reduction_proxy_service(DataReductionProxyService* service) {
+    service_ = service;
+  }

[jeremyim, 2015/07/13 20:19:40]

Looks like this is part of a future CL that crept in here? |service_| appears to
be unused.

[Not at Google. Contact bengr, 2015/07/14 16:41:30]

I intended to have this be part of this cl, since this is part of the hookup.

All of the functionality in this cl is unused. Cl is already pretty big, so
seemed better to split from cl that uses this functionality. 

[jeremyim, 2015/07/14 22:39:54]

I'll likely have some comments about this in the next CL; in general, I'm not a
fan of having to perform a set call, since it introduces the possibility of data
races.

[Not at Google. Contact bengr, 2015/07/15 00:08:17]

Done.

+
  private:
   friend class DataReductionProxyCompressionStatsTest;
 
@@ -145,6 +155,7 @@ class DataReductionProxyCompressionStats {
   DataReductionProxyListPrefMap list_pref_map_;
   scoped_ptr<PrefChangeRegistrar> pref_change_registrar_;
   base::ThreadChecker thread_checker_;
+  DataReductionProxyService* service_;
 
   base::WeakPtrFactory<DataReductionProxyCompressionStats> weak_factory_;