Record DRP histogram on how long back savings were cleared

components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_SETTINGS_H_
 #define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_SETTINGS_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 252 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            TestLoFiSessionStateHistograms);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            TestSettingsEnabledStateHistograms);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            TestDaysSinceEnabled);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            TestDaysSinceEnabledWithTestClock);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            TestDaysSinceEnabledExistingUser);
+  FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
+                           TestDaysSinceSavingsCleared);
 
   // Override of DataReductionProxyService::Observer.
   void OnServiceInitialized() override;
 
   // Registers the trial "SyntheticDataReductionProxySetting" with the group
   // "Enabled" or "Disabled". Indicates whether the proxy is turned on or not.
   void RegisterDataReductionProxyFieldTrial();
 
   void OnProxyEnabledPrefChange();
 
@@ skipping 59 matching lines @@
   std::unique_ptr<base::Clock> clock_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(DataReductionProxySettings);
 };
 
 }  // namespace data_reduction_proxy
 
 #endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_SETTINGS_H_