Add testing for subscription from service workers

chrome/browser/push_messaging/push_messaging_permission_context.cc

 // Copyright 2014 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/push_messaging/push_messaging_permission_context.h"
 
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "chrome/browser/notifications/notification_permission_context.h"
 #include "chrome/browser/notifications/notification_permission_context_factory.h"
 #include "chrome/browser/permissions/permission_request_id.h"
@@ skipping 35 matching lines @@
   DCHECK(notification_context);
 
   ContentSetting notifications_permission =
       notification_context->GetPermissionStatus(requesting_origin,
                                                 embedding_origin);
 
   if (notifications_permission == CONTENT_SETTING_BLOCK ||
       push_content_setting == CONTENT_SETTING_BLOCK) {
     return CONTENT_SETTING_BLOCK;
   }
-  if (notifications_permission == CONTENT_SETTING_ASK ||
-      push_content_setting == CONTENT_SETTING_ASK) {
+  if (notifications_permission == CONTENT_SETTING_ASK)
     return CONTENT_SETTING_ASK;
-  }
-  DCHECK_EQ(CONTENT_SETTING_ALLOW, notifications_permission);
-  DCHECK_EQ(CONTENT_SETTING_ALLOW, push_content_setting);
+
+  DCHECK(push_content_setting == CONTENT_SETTING_ALLOW ||
+         push_content_setting == CONTENT_SETTING_ASK);
+
+  // If the notifications permission has already been granted,
+  // and the push permission isn't explicitly blocked, then grant
+  // allow permission.
   return CONTENT_SETTING_ALLOW;
 #else
   return CONTENT_SETTING_BLOCK;
 #endif
 }
 
 // Unlike other permissions, push is decided by the following algorithm
 //  - You need to request it from a top level domain
 //  - You need to have notification permission granted.
 //  - You need to not have push permission explicitly blocked.
@@ skipping 57 matching lines @@
     DVLOG(1) << "Notification permission has not been granted.";
     NotifyPermissionSet(id, requesting_origin, embedding_origin, callback,
                         false /* persist */, notification_content_setting);
     return;
   }
 
   PermissionUmaUtil::PermissionGranted(permission_type(), requesting_origin);
   NotifyPermissionSet(id, requesting_origin, embedding_origin, callback,
                       true /* persist */, CONTENT_SETTING_ALLOW);
 }