Delete long-expired GlobalSdch field trial.

chrome/renderer/page_load_histograms.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/renderer/page_load_histograms.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 393 matching lines @@
     PLT_HISTOGRAM("PLT.BeginToFinish_ContentPrefetcher",
                   begin_to_finish_all_loads);
   }
   if (document_state->was_referred_by_prefetcher()) {
     PLT_HISTOGRAM("PLT.BeginToFinishDoc_ContentPrefetcherReferrer",
                   begin_to_finish_doc);
     PLT_HISTOGRAM("PLT.BeginToFinish_ContentPrefetcherReferrer",
                   begin_to_finish_all_loads);
   }
 
-  // Histograms to determine if SDCH has an impact.
-  // TODO(jar): Consider removing per-link load types and the enumeration.
-  static const bool use_sdch_histogram =
-      base::FieldTrialList::TrialExists("GlobalSdch");
-  if (use_sdch_histogram) {
-    UMA_HISTOGRAM_ENUMERATION(
-        base::FieldTrial::MakeName("PLT.LoadType", "GlobalSdch"),
-        load_type, DocumentState::kLoadTypeMax);
-    switch (load_type) {
-      case DocumentState::NORMAL_LOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_NormalLoad", "GlobalSdch"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_NORMAL:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadNormal", "GlobalSdch"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_RELOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadReload", "GlobalSdch"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_CACHE_STALE_OK:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadStaleOk", "GlobalSdch"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_CACHE_ONLY:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadCacheOnly", "GlobalSdch"),
-            begin_to_finish_all_loads);
-        break;
-      default:
-        break;
-    }
-  }
-
   // TODO(mpcomplete): remove the extension-related histograms after we collect
   // enough data. http://crbug.com/100411
   const bool use_adblock_histogram =
       chrome::ChromeContentRendererClient::IsAdblockInstalled();
   if (use_adblock_histogram) {
     UMA_HISTOGRAM_ENUMERATION(
         "PLT.Abandoned_ExtensionAdblock",
         abandoned_page ? 1 : 0, 2);
     switch (load_type) {
       case DocumentState::NORMAL_LOAD:
@@ skipping 286 matching lines @@
 
   DCHECK(document_state);
   DCHECK(ds);
   GURL url(ds->request().url());
   Time start = document_state->start_load_time();
   Time finish = document_state->finish_load_time();
   // TODO(mbelshe): should we log more stats?
   VLOG(1) << "PLT: " << (finish - start).InMilliseconds() << "ms "
           << url.spec();
 }