Adding a parameter for previews NQE triggering threshold

components/previews/core/previews_io_data.cc

 // 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.
 
 #include "components/previews/core/previews_io_data.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_path.h"
 #include "base/location.h"
@@ skipping 95 matching lines @@
   net::NetworkQualityEstimator* network_quality_estimator =
       request.context()->network_quality_estimator();
   if (!network_quality_estimator ||
       network_quality_estimator->GetEffectiveConnectionType() <
           net::EFFECTIVE_CONNECTION_TYPE_OFFLINE) {
     LogPreviewsEligibilityReason(
         PreviewsEligibilityReason::NETWORK_QUALITY_UNAVAILABLE, type);
     return false;
   }
   if (network_quality_estimator->GetEffectiveConnectionType() >
-      net::EFFECTIVE_CONNECTION_TYPE_SLOW_2G) {
+      params::EffectiveConnectionTypeThreshold()) {
     LogPreviewsEligibilityReason(PreviewsEligibilityReason::NETWORK_NOT_SLOW,
                                  type);
     return false;
   }
   // LOAD_VALIDATE_CACHE or LOAD_BYPASS_CACHE mean the user reloaded the page.
   // If this is a query for offline previews, reloads should be disallowed.
   if (type == PreviewsType::OFFLINE &&
       request.load_flags() &
           (net::LOAD_VALIDATE_CACHE | net::LOAD_BYPASS_CACHE)) {
     LogPreviewsEligibilityReason(
         PreviewsEligibilityReason::RELOAD_DISALLOWED_FOR_OFFLINE, type);
     return false;
   }
   LogPreviewsEligibilityReason(PreviewsEligibilityReason::ALLOWED, type);
   return true;
 }
 
 }  // namespace previews