Throttle websocket live experiment

chrome/browser/net/websocket_experiment/websocket_experiment_runner.cc

 // Copyright (c) 2009 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/net/websocket_experiment/websocket_experiment_runner.h"
 
 #include "base/compiler_specific.h"
+#include "base/field_trial.h"
 #include "base/histogram.h"
 #include "base/message_loop.h"
 #include "base/task.h"
 #include "chrome/browser/chrome_thread.h"
 #include "net/base/net_errors.h"
 
 namespace chrome_browser_net_websocket_experiment {
 
 static const char *kExperimentHost = "websocket-experiment.chromium.org";
 static const int kAlternativePort = 61985;
@@ skipping 74 matching lines @@
         break;                                                          \
     }                                                                   \
   } while (0);
 
 // Hold reference while experiment is running.
 static scoped_refptr<WebSocketExperimentRunner> runner;
 
 /* static */
 void WebSocketExperimentRunner::Start() {
   DCHECK(!runner.get());
+
+  scoped_refptr<FieldTrial> trial = new FieldTrial("WebSocketExperiment", 1000);
+  trial->AppendGroup("_active", 5);  // 0.5% in _active group.
+
+  if (trial->group() == FieldTrial::kNotParticipating)
+    return;
+
   runner = new WebSocketExperimentRunner;
   runner->Run();
 }
 
 /* static */
 void WebSocketExperimentRunner::Stop() {
   if (runner.get())
     runner->Cancel();
   runner = NULL;
 }
@@ skipping 190 matching lines @@
       WebSocketExperimentTask::STATE_WEBSOCKET_CLOSE_COMPLETE)
     return;
 
   UPDATE_HISTOGRAM_TIMES("WebSocketTotal", task_result.websocket_total,
                          base::TimeDelta::FromMilliseconds(1),
                          base::TimeDelta::FromSeconds(kWebSocketTimeSec),
                          kTimeBucketCount);
 }
 
 }  // namespace chrome_browser_net_websocket_experiment