Resetting metrics ids on clump detection.

chrome/browser/chrome_browser_main.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/chrome_browser_main.h"
 
 #if defined(TOOLKIT_GTK)
 #include <gtk/gtk.h>
 #endif
 
@@ skipping 560 matching lines @@
   // Must initialize metrics after labs have been converted into switches,
   // but before field trials are set up (so that client ID is available for
   // one-time randomized field trials).
 #if defined(ARCH_CPU_64_BITS)
   MetricsLog::set_version_extension("-64");
 #endif  // defined(ARCH_CPU_64_BITS)
 
   // Initialize FieldTrialList to support FieldTrials that use one-time
   // randomization.
   MetricsService* metrics = browser_process_->metrics_service();
+
+  if (local_state_->GetBoolean(prefs::kMetricsCloneDetected))
+    metrics->ResetVariationsState();

[Alexei Svitkine (slow), 2014/03/26 21:34:50]

Hmm, I'd actually prefer that the logic be entirely in MetricsService.

Maybe we can make the new function do the pref check itself and then call it
from both ForceClientIdCreation() and GetLowEntropySource().

[jwd, 2014/03/28 16:23:49]

Done.

+
   MetricsService::ReportingState reporting_state =
       IsMetricsReportingEnabled() ? MetricsService::REPORTING_ENABLED :
                                     MetricsService::REPORTING_DISABLED;
   if (reporting_state == MetricsService::REPORTING_ENABLED)
     metrics->ForceClientIdCreation();  // Needed below.
   field_trial_list_.reset(
       new base::FieldTrialList(
           metrics->CreateEntropyProvider(reporting_state).release()));
 
   const CommandLine* command_line = CommandLine::ForCurrentProcess();
@@ skipping 1104 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif
 #endif
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }