Add a policy to disable mounting of external storage.

chrome/browser/chromeos/preferences.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/chromeos/preferences.h"
 
 #include "base/chromeos/chromeos_version.h"
 #include "base/command_line.h"
 #include "base/i18n/time_formatting.h"
 #include "base/metrics/histogram.h"
@@ skipping 250 matching lines @@
                             PrefService::UNSYNCABLE_PREF);
   prefs->RegisterStringPref(prefs::kOAuth1Secret,
                             "",
                             PrefService::UNSYNCABLE_PREF);
 
   // TODO(wad): Once UI is connected, a final default can be set. At that point
   // change this pref from UNSYNCABLE to SYNCABLE.
   prefs->RegisterBooleanPref(prefs::kEnableCrosDRM,
                              true,
                              PrefService::UNSYNCABLE_PREF);
+
+  prefs->RegisterBooleanPref(prefs::kExternalStorageDisabled,
+                             false,
+                             PrefService::UNSYNCABLE_PREF);
 }
 
 void Preferences::InitUserPrefs(PrefService* prefs) {
   tap_to_click_enabled_.Init(prefs::kTapToClickEnabled, prefs, this);
   three_finger_click_enabled_.Init(prefs::kEnableTouchpadThreeFingerClick,
       prefs, this);
   natural_scroll_.Init(prefs::kNaturalScroll, prefs, this);
   accessibility_enabled_.Init(prefs::kSpokenFeedbackEnabled, prefs, this);
   mouse_sensitivity_.Init(prefs::kMouseSensitivity, prefs, this);
   touchpad_sensitivity_.Init(prefs::kTouchpadSensitivity, prefs, this);
@@ skipping 373 matching lines @@
 
   input_method::AutoRepeatRate rate;
   rate.initial_delay_in_ms = xkb_auto_repeat_delay_pref_.GetValue();
   rate.repeat_interval_in_ms = xkb_auto_repeat_interval_pref_.GetValue();
   DCHECK(rate.initial_delay_in_ms > 0);
   DCHECK(rate.repeat_interval_in_ms > 0);
   input_method::XKeyboard::SetAutoRepeatRate(rate);
 }
 
 }  // namespace chromeos