Temporary whitelist several cases of disk I/O on the UI threads in cros.

chrome/browser/chromeos/metrics_cros_settings_provider.cc

 // Copyright (c) 2010 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/chromeos/metrics_cros_settings_provider.h"
 
 #include "base/string_util.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/cros_settings.h"
 #include "chrome/browser/chromeos/cros_settings_names.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/ui/options/options_util.h"
 #include "chrome/installer/util/google_update_settings.h"
 
 #if defined(USE_LINUX_BREAKPAD)
 #include "chrome/app/breakpad_linux.h"
 #endif
@@ skipping 18 matching lines @@
 }
 
 // static
 bool MetricsCrosSettingsProvider::SetMetricsStatus(bool enabled) {
   // We must be not logged in (on EULA page) or logged is as an owner to be able
   // to modify the setting.
   UserManager *user = UserManager::Get();
   if (user->user_is_logged_in() && !user->current_user_is_owner())
     return false;
   VLOG(1) << "Setting cros stats/crash metric reporting to " << enabled;
-  if (enabled != GoogleUpdateSettings::GetCollectStatsConsent()) {
+  bool collect_stats_consent = false;
+  {
+    // Loading consent file state causes us to do blocking IO on UI thread.
+    // Temporarily allow it until we fix http://crbug.com/62626
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    collect_stats_consent = GoogleUpdateSettings::GetCollectStatsConsent();
+  }
+  if (enabled != collect_stats_consent) {
     bool new_enabled = OptionsUtil::ResolveMetricsReportingEnabled(enabled);
 #if defined(USE_LINUX_BREAKPAD)
     if (new_enabled)
       InitCrashReporter();
     // Else, if (!new_enabled), we should have turned crash reporting off
     // here, but there is no API for that currently (while we use
     // BreakPad). But this is not a big deal: crash reporting will be off
     // after reboot for the current process while other Chrome processes
     // will start when the setting is already set up. Other ChromeOS
     // processes does not use BreakPad.
 #endif
     return new_enabled == enabled;
   }
   return false;
 }
 
 // static
 bool MetricsCrosSettingsProvider::GetMetricsStatus() {
+  // Loading consent file state causes us to do blocking IO on UI thread.
+  // Temporarily allow it until we fix http://crbug.com/62626
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   return GoogleUpdateSettings::GetCollectStatsConsent();
 }
 
 bool MetricsCrosSettingsProvider::HandlesSetting(const std::string& path) {
   return ::StartsWithASCII(path, kStatsReportingPref, true);
 }
 
 };  // namespace chromeos