Adding a parameter for previews NQE triggering threshold

components/previews/core/previews_experiments.h

 // Copyright 2016 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_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_
 #define COMPONENTS_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_
 
 #include "base/time/time.h"
+#include "net/nqe/effective_connection_type.h"
 
 namespace previews {
 
 namespace params {
 
 // The maximum number of recent previews navigations the black list looks at to
 // determine if a host is blacklisted.
 size_t MaxStoredHistoryLengthForPerHostBlackList();
 
 // The maximum number of recent previews navigations the black list looks at to
@@ skipping 17 matching lines @@
 // The amount of time all previews navigations are disallowed due to opt outs.
 base::TimeDelta HostIndifferentBlackListPerHostDuration();
 
 // The amount of time after any opt out that no previews should be shown.
 base::TimeDelta SingleOptOutDuration();
 
 // The amount of time that an offline page is considered fresh enough to be
 // shown as a preview.
 base::TimeDelta OfflinePreviewFreshnessDuration();
 
+// The threshold of EffectiveConnectionType above which previews should not be
+// served.
+net::EffectiveConnectionType EffectiveConnectionTypeThreshold();
+
 }  // namespace params
 
 enum class PreviewsType {
   NONE = 0,
   OFFLINE = 1,
   LAST = 2,
 };
 
 // Returns true if any client-side previews experiment is active.
 bool IsIncludedInClientSidePreviewsExperimentsFieldTrial();
 
 // Returns true if the field trial that should enable previews for |type| for
 // prohibitvely slow networks is active.
 bool IsPreviewsTypeEnabled(PreviewsType type);
 
 // Sets the appropriate state for field trial and variations to imitate the
 // offline pages field trial.
 bool EnableOfflinePreviewsForTesting();
 
 }  // namespace previews
 
 #endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_