Add DataReductionProxyExperimentsStats and UMA for measuring potentially non-compressed bytes.

components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
index d68001f63f88e98cd5db66e1de270c8108fcca34..d9747dab969a334a4941efc24f8b16a74e2ec416 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
@@ -34,6 +34,7 @@ class DataReductionProxyConfig;
 class DataReductionProxyConfigServiceClient;
 class DataReductionProxyConfigurator;
 class DataReductionProxyEventCreator;
+class DataReductionProxyExperimentsStats;
 class DataReductionProxyService;
 
 // Contains and initializes all Data Reduction Proxy objects that operate on
@@ -124,6 +125,10 @@ class DataReductionProxyIOData : public DataReductionProxyEventStorageDelegate {
     return config_client_.get();
   }
 
+  DataReductionProxyExperimentsStats* experiments_stats() const {
+    return experiments_stats_.get();
+  }
+
   net::ProxyDelegate* proxy_delegate() const {
     return proxy_delegate_.get();
   }
@@ -165,6 +170,9 @@ class DataReductionProxyIOData : public DataReductionProxyEventStorageDelegate {
   // Records that the data reduction proxy is unreachable or not.
   void SetUnreachable(bool unreachable);
 
+  // Stores an int64 value in preferences storage.
+  void SetInt64Pref(const std::string& pref_path, int64 value);
+
   // The type of Data Reduction Proxy client.
   Client client_;
 
@@ -197,6 +205,9 @@ class DataReductionProxyIOData : public DataReductionProxyEventStorageDelegate {
   // Requests new Data Reduction Proxy configurations from a remote service.
   scoped_ptr<DataReductionProxyConfigServiceClient> config_client_;
 
+  // Used to track stats for experiments.
+  scoped_ptr<DataReductionProxyExperimentsStats> experiments_stats_;
+
   // A net log.
   net::NetLog* net_log_;