Revert of Revert of chromeos: Don't send empty power management policies.

chrome/browser/chromeos/power/power_prefs.cc

 // Copyright 2013 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/power/power_prefs.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/logging.h"
@@ skipping 219 matching lines @@
 
 void PowerPrefs::SetProfile(Profile* profile) {
   // No need to reapply policy if profile hasn't changed, e.g. when adding a
   // secondary user to an existing session.
   if (profile == profile_)
     return;
 
   profile_ = profile;
   pref_change_registrar_.reset();
 
-  if (!profile) {
-    power_policy_controller_->ClearPrefs();
+  if (!profile)
     return;
-  }
 
   base::Closure update_callback(base::Bind(
       &PowerPrefs::UpdatePowerPolicyFromPrefs,
       base::Unretained(this)));
   pref_change_registrar_.reset(new PrefChangeRegistrar);
   pref_change_registrar_->Init(profile->GetPrefs());
   pref_change_registrar_->Add(prefs::kPowerAcScreenDimDelayMs, update_callback);
   pref_change_registrar_->Add(prefs::kPowerAcScreenOffDelayMs, update_callback);
   pref_change_registrar_->Add(prefs::kPowerAcScreenLockDelayMs,
                               update_callback);
@@ skipping 21 matching lines @@
                               update_callback);
   pref_change_registrar_->Add(prefs::kPowerUserActivityScreenDimDelayFactor,
                               update_callback);
   pref_change_registrar_->Add(prefs::kPowerWaitForInitialUserActivity,
                               update_callback);
 
   UpdatePowerPolicyFromPrefs();
 }
 
 }  // namespace chromeos