Remove the unmaintained performance monitor.

chrome/browser/about_flags.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/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 1087 matching lines @@
         password_manager::switches::kDisableAndroidPasswordLink)
   },
   {
     "enable-deferred-image-decoding",
     IDS_FLAGS_ENABLE_DEFERRED_IMAGE_DECODING_NAME,
     IDS_FLAGS_ENABLE_DEFERRED_IMAGE_DECODING_DESCRIPTION,
     kOsMac | kOsLinux | kOsCrOS,
     SINGLE_VALUE_TYPE(switches::kEnableDeferredImageDecoding)
   },
   {
-    "performance-monitor-gathering",
-    IDS_FLAGS_PERFORMANCE_MONITOR_GATHERING_NAME,
-    IDS_FLAGS_PERFORMANCE_MONITOR_GATHERING_DESCRIPTION,
-    kOsAll,
-    SINGLE_VALUE_TYPE(switches::kPerformanceMonitorGathering)
-  },
-  {
     "wallet-service-use-sandbox",
     IDS_FLAGS_WALLET_SERVICE_USE_SANDBOX_NAME,
     IDS_FLAGS_WALLET_SERVICE_USE_SANDBOX_DESCRIPTION,
     kOsAndroid | kOsDesktop,
     ENABLE_DISABLE_VALUE_TYPE_AND_VALUE(
         autofill::switches::kWalletServiceUseSandbox, "1",
         autofill::switches::kWalletServiceUseSandbox, "0")
   },
 #if defined(USE_AURA)
   {
@@ skipping 1362 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags