Make running the outdated build detector conditional on a Feature.

chrome/browser/upgrade_detector_impl.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/upgrade_detector_impl.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/bind.h"
 #include "base/build_time.h"
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/memory/singleton.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 361 matching lines @@
   // We use FILE as the thread to run the upgrade detection code on all
   // platforms. For Linux, this is because we don't want to block the UI thread
   // while launching a background process and reading its output; on the Mac and
   // on Windows checking for an upgrade requires reading a file.
   BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
                           base::Bind(&UpgradeDetectorImpl::DetectUpgradeTask,
                                      weak_factory_.GetWeakPtr()));
 }
 
 bool UpgradeDetectorImpl::DetectOutdatedInstall() {
+  constexpr base::Feature kOutdatedBuildDetector =

[grt (UTC plus 2), 2016/08/23 08:54:44]

thakis: should this really be:
  static constexpr base::Feature ...
so that the struct isn't put on the stack in each invocation?

+      { "OutdatedBuildDetector", base::FEATURE_ENABLED_BY_DEFAULT };
+
+  if (!base::FeatureList::IsEnabled(kOutdatedBuildDetector))
+    return false;
+
   // Don't show the bubble if we have a brand code that is NOT organic, unless
   // an outdated build is being simulated by command line switches.
   static bool simulate_outdated = SimulatingOutdated();
   if (!simulate_outdated) {
     std::string brand;
     if (google_brand::GetBrand(&brand) && !google_brand::IsOrganic(brand))
       return false;
 
 #if defined(OS_WIN)
     // Don't show the update bubbles to enterprise users (i.e., on a domain).
@@ skipping 108 matching lines @@
 
 // static
 UpgradeDetectorImpl* UpgradeDetectorImpl::GetInstance() {
   return base::Singleton<UpgradeDetectorImpl>::get();
 }
 
 // static
 UpgradeDetector* UpgradeDetector::GetInstance() {
   return UpgradeDetectorImpl::GetInstance();
 }