Update from https://crrev.com/320343

base/prefs/json_pref_store.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 "base/prefs/json_pref_store.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
-#include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
-#include "base/prefs/base_prefs_switches.h"
 #include "base/prefs/pref_filter.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/values.h"
 
 // Result returned from internal read tasks.
 struct JsonPrefStore::ReadResult {
  public:
@@ skipping 364 matching lines @@
   CommitPendingWrite();
 }
 
 bool JsonPrefStore::SerializeData(std::string* output) {
   DCHECK(CalledOnValidThread());
 
   if (pref_filter_)
     pref_filter_->FilterSerializeData(prefs_.get());
 
   JSONStringValueSerializer serializer(output);
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kPrettyPrintPrefs)) {
-    serializer.set_pretty_print(true);
-  }
+  // Not pretty-printing prefs shrinks pref file size by ~30%. To obtain
+  // readable prefs for debugging purposes, you can dump your prefs into any
+  // command-line or online JSON pretty printing tool.
+  serializer.set_pretty_print(false);
   return serializer.Serialize(*prefs_);
 }
 
 void JsonPrefStore::FinalizeFileRead(bool initialization_successful,
                                      scoped_ptr<base::DictionaryValue> prefs,
                                      bool schedule_write) {
   DCHECK(CalledOnValidThread());
 
   filtering_in_progress_ = false;
 
@@ skipping 13 matching lines @@
 
   if (error_delegate_ && read_error_ != PREF_READ_ERROR_NONE)
     error_delegate_->OnError(read_error_);
 
   FOR_EACH_OBSERVER(PrefStore::Observer,
                     observers_,
                     OnInitializationCompleted(true));
 
   return;
 }