Fix bug: MIDI causes crash on onContentSettingChanged()

chrome/browser/permissions/permission_manager.cc

 // Copyright 2015 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/permissions/permission_manager.h"
 
 #include <stddef.h>
 
 #include "base/callback.h"
 #include "build/build_config.h"
@@ skipping 380 matching lines @@
 void PermissionManager::OnContentSettingChanged(
     const ContentSettingsPattern& primary_pattern,
     const ContentSettingsPattern& secondary_pattern,
     ContentSettingsType content_type,
     std::string resource_identifier) {
   std::list<base::Closure> callbacks;
 
   for (SubscriptionsMap::iterator iter(&subscriptions_);
        !iter.IsAtEnd(); iter.Advance()) {
     Subscription* subscription = iter.GetCurrentValue();
+    if (IsConstantPermission(subscription->permission))
+      continue;
     if (PermissionTypeToContentSetting(subscription->permission) !=
         content_type) {
       continue;
     }
 
     if (primary_pattern.IsValid() &&
         !primary_pattern.Matches(subscription->requesting_origin))
       continue;
     if (secondary_pattern.IsValid() &&
         !secondary_pattern.Matches(subscription->embedding_origin))
@@ skipping 11 matching lines @@
     // Add the callback to |callbacks| which will be run after the loop to
     // prevent re-entrance issues.
     callbacks.push_back(
         base::Bind(subscription->callback,
                    ContentSettingToPermissionStatus(new_value)));
   }
 
   for (const auto& callback : callbacks)
     callback.Run();
 }