Add field trial for A/B testing of SSL False Start.

chrome/renderer/page_load_histograms.cc

 // Copyright (c) 2010 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 "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/time.h"
@@ skipping 778 matching lines @@
                                 abandoned_page ? 1 : 0, 2);
     } else {
       DCHECK(scheme_type == URLPattern::SCHEME_HTTP);
       PLT_HISTOGRAM("PLT.StartToFinish.NoProxy.http",
                     start_to_finish_all_loads);
       UMA_HISTOGRAM_ENUMERATION("PLT.Abandoned.NoProxy.http",
                                 abandoned_page ? 1 : 0, 2);
     }
   }
 
+  static bool false_start_trial(base::FieldTrialList::Find("SSLFalseStart") &&
+      !base::FieldTrialList::Find("SSLFalseStart")->group_name().empty());
+  if (false_start_trial) {
+    if (scheme_type == URLPattern::SCHEME_HTTPS) {
+      switch (load_type) {
+        case NavigationState::LINK_LOAD_NORMAL:
+          PLT_HISTOGRAM(base::FieldTrial::MakeName(
+              "PLT.BeginToFinish_LinkLoadNormal", "SSLFalseStart"),
+              begin_to_finish_all_loads);
+          break;
+        case NavigationState::NORMAL_LOAD:
+          PLT_HISTOGRAM(base::FieldTrial::MakeName(
+              "PLT.BeginToFinish_NormalLoad", "SSLFalseStart"),
+              begin_to_finish_all_loads);
+          break;
+        default:
+          break;
+      }
+    }
+  }
+
   // Site isolation metrics.
   UMA_HISTOGRAM_COUNTS("SiteIsolation.PageLoadsWithCrossSiteFrameAccess",
                        cross_origin_access_count_);
   UMA_HISTOGRAM_COUNTS("SiteIsolation.PageLoadsWithSameSiteFrameAccess",
                        same_origin_access_count_);
 
   // Log the PLT to the info log.
   LogPageLoadTime(navigation_state, frame->dataSource());
 
   // Since there are currently no guarantees that renderer histograms will be
@@ skipping 31 matching lines @@
 
   DCHECK(state);
   DCHECK(ds);
   GURL url(ds->request().url());
   Time start = state->start_load_time();
   Time finish = state->finish_load_time();
   // TODO(mbelshe): should we log more stats?
   VLOG(1) << "PLT: " << (finish - start).InMilliseconds() << "ms "
           << url.spec();
 }