Do not disable Data Reduction Proxy on VPN.

components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
index f9b83c1e8fe280047e2572c4f8e7e69b0f88121d..2fc3bdbba07610201c11e0bd654f5ccc3773728d 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
@@ -242,6 +242,10 @@ class DataReductionProxyConfig
                            AreProxiesBypassed);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxyConfigTest,
                            AreProxiesBypassedRetryDelay);
+  FRIEND_TEST_ALL_PREFIXES(DataReductionProxyConfigTest,
+                           TestMaybeDisableIfVPNTrialDisabled);
+  FRIEND_TEST_ALL_PREFIXES(DataReductionProxyConfigTest,
+                           TestMaybeDisableIfVPNTrialEnabled);
 
   // NetworkChangeNotifier::IPAddressObserver:
   void OnIPAddressChanged() override;
@@ -267,9 +271,10 @@ class DataReductionProxyConfig
   // Adds the default proxy bypass rules for the Data Reduction Proxy.
   void AddDefaultProxyBypassRules();
 
-  // Disables use of the Data Reduction Proxy on VPNs. Returns true if the
-  // Data Reduction Proxy has been disabled.
-  bool DisableIfVPN();
+  // Disables use of the Data Reduction Proxy on VPNs if client is not in the
+  // DataReductionProxyUseDataSaverOnVPN field trial and a TUN network interface
+  // is being used. Returns true if the Data Reduction Proxy has been disabled.
+  bool MaybeDisableIfVPN();
 
   // Checks if all configured data reduction proxies are in the retry map.
   // Returns true if the request is bypassed by all configured data reduction