Added data reduction proxy holdback experiment

components/data_reduction_proxy/browser/data_reduction_proxy_params.cc

Index: components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
index 3ef81d3d332d3561e26cfe46eea5d060c552164a..94e266858c8a657f014df9f20ab88b1cd76de62e 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
@@ -45,11 +45,18 @@ bool DataReductionProxyParams::IsIncludedInPreconnectHintingFieldTrial() {
           "DataCompressionProxyPreconnectHints") == kEnabled;
 }
 
+// static
+bool DataReductionProxyParams::IsIncludedInHoldbackFieldTrial() {
+  return FieldTrialList::FindFullName(
+      "DataCompressionProxyHoldback") == kEnabled;
+}
+
 DataReductionProxyParams::DataReductionProxyParams(int flags)
     : allowed_((flags & kAllowed) == kAllowed),
       fallback_allowed_((flags & kFallbackAllowed) == kFallbackAllowed),
       alt_allowed_((flags & kAlternativeAllowed) == kAlternativeAllowed),
       promo_allowed_((flags & kPromoAllowed) == kPromoAllowed),
+      holdback_((flags & kHoldback) == kHoldback),
       configured_on_command_line_(false) {
   bool result = Init(allowed_, fallback_allowed_, alt_allowed_);
   DCHECK(result);