renderer: implement multiple permission requesting

content/browser/permissions/permission_pending_request.h

+// 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.
+
+#ifndef CONTENT_BROWSER_PERMISSIONS_PERMISSION_PENDING_REQUEST_H_
+#define CONTENT_BROWSER_PERMISSIONS_PERMISSION_PENDING_REQUEST_H_
+
+#include "base/callback_forward.h"
+
+namespace content {
+
+class PermissionManager;
+class RenderFrameHost;
+
+class PermissionPendingRequest {
+ public:
+  virtual ~PermissionPendingRequest() {};
+
+  virtual void Cancel(PermissionManager* permission_manager,
+                      RenderFrameHost* context,
+                      int request_id) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_PERMISSIONS_PERMISSION_PENDING_REQUEST_H_