Revert of Prerender: Hardcode the Silence experiment date

chrome/browser/prerender/prerender_manager.cc

 // Copyright (c) 2012 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 "chrome/browser/prerender/prerender_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <functional>
@@ skipping 1243 matching lines @@
     return;
   int64_t recent_profile_bytes =
       profile_network_bytes_ - last_recorded_profile_network_bytes_;
   last_recorded_profile_network_bytes_ = profile_network_bytes_;
   DCHECK_GE(recent_profile_bytes, 0);
   histograms_->RecordNetworkBytes(
       origin, used, prerender_bytes, recent_profile_bytes);
 }
 
 bool PrerenderManager::IsPrerenderSilenceExperiment(Origin origin) const {
-  if (origin == ORIGIN_OFFLINE ||
-      origin == ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR) {
+  if (origin == ORIGIN_OFFLINE)
     return false;
-  }
 
   // The group name should contain expiration time formatted as:
   //   "ExperimentYes_expires_YYYY-MM-DDTHH:MM:SSZ".
   std::string group_name =
       base::FieldTrialList::FindFullName("PrerenderSilence");
   const char kExperimentPrefix[] = "ExperimentYes";
   if (!base::StartsWith(group_name, kExperimentPrefix,
                         base::CompareCase::INSENSITIVE_ASCII)) {
-    // The experiment group was not set, use 2016-12-14 PST as the day of the
-    // experiment.
-    base::Time experiment_start;
-    if (!base::Time::FromString("2016-12-14-08:00:00Z", &experiment_start))
-      NOTREACHED();
-    base::Time current_time = GetCurrentTime();
-    if ((experiment_start <= current_time) &&
-        (current_time < experiment_start + base::TimeDelta::FromDays(1))) {
-      return true;
-    }
     return false;
   }
   const char kExperimentPrefixWithExpiration[] = "ExperimentYes_expires_";
   if (!base::StartsWith(group_name, kExperimentPrefixWithExpiration,
                         base::CompareCase::INSENSITIVE_ASCII)) {
     // Without expiration day in the group name, behave as a normal experiment,
     // i.e. sticky to the Chrome session.
     return true;
   }
   base::Time expiration_time;
@@ skipping 77 matching lines @@
   return weak_factory_.GetWeakPtr();
 }
 
 void PrerenderManager::SetPrerenderContentsFactoryForTest(
     PrerenderContents::Factory* prerender_contents_factory) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   prerender_contents_factory_.reset(prerender_contents_factory);
 }
 
 }  // namespace prerender