Add getUserSelectedDevices to the USB extensions API.

chrome/browser/extensions/api/chrome_device_permissions_prompt.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 CHROME_BROWSER_EXTENSIONS_API_CHROME_DEVICE_PERMISSIONS_PROMPT_H_
+#define CHROME_BROWSER_EXTENSIONS_API_CHROME_DEVICE_PERMISSIONS_PROMPT_H_
+
+#include "extensions/browser/api/device_permissions_prompt.h"
+
+class ChromeDevicePermissionsPrompt
+    : public extensions::DevicePermissionsPrompt {
+ public:
+  explicit ChromeDevicePermissionsPrompt(content::WebContents* web_contents)
+      : extensions::DevicePermissionsPrompt(web_contents) {}
+
+  virtual ~ChromeDevicePermissionsPrompt() {}
+
+ private:
+  virtual void ShowDialog() override;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_CHROME_DEVICE_PERMISSIONS_PROMPT_H_