Give PlatformNotificationAction's scalar type field a default value

content/public/common/platform_notification_data.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_COMMON_PLATFORM_NOTIFICATION_DATA_H_
 #define CONTENT_PUBLIC_COMMON_PLATFORM_NOTIFICATION_DATA_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 13 matching lines @@
 };
 
 // A notification action (button or text input); corresponds to Blink
 // WebNotificationAction.
 struct CONTENT_EXPORT PlatformNotificationAction {
   PlatformNotificationAction();
   PlatformNotificationAction(const PlatformNotificationAction& other);
   ~PlatformNotificationAction();
 
   // Type of the action (button or text input).
-  PlatformNotificationActionType type;
+  PlatformNotificationActionType type =
+      PLATFORM_NOTIFICATION_ACTION_TYPE_BUTTON;
 
   // Action name that the author can use to distinguish them.
   std::string action;
 
   // Title of the button.
   base::string16 title;
 
   // URL of the icon for the button. May be empty if no url was specified.
   GURL icon;
 
@@ skipping 72 matching lines @@
   // a serialized string. Must not exceed |kMaximumDeveloperDataSize| bytes.
   std::vector<char> data;
 
   // Actions that should be shown as buttons on the notification.
   std::vector<PlatformNotificationAction> actions;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_PLATFORM_NOTIFICATION_DATA_H_