Add chrome side webusb permission UI code

chrome/browser/ui/website_settings/chooser_choices.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 CHROME_BROWSER_UI_WEBSITE_SETTINGS_CHOOSER_CHOICES_H_
+#define CHROME_BROWSER_UI_WEBSITE_SETTINGS_CHOOSER_CHOICES_H_
+
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+
+// Stores all the available device lists, handle device added/removed, etc.
+class ChooserChoices {

[Reilly Grant (use Gerrit), 2015/11/12 21:44:36]

s/Choice/Option/g and I think these class and method names will read better.

[juncai, 2015/11/14 01:54:36]

Done.

+ public:
+  ChooserChoices() {}
+  virtual ~ChooserChoices() {}
+
+  class Observer {
+   public:
+    virtual void OnChoicesInitialized() = 0;
+    virtual void OnChoiceAdded(int index) = 0;
+    virtual void OnChoiceRemoved(int index) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  virtual const std::vector<std::string>& GetChoices() const = 0;
+  virtual void Select(int index) = 0;
+
+  void set_observer(Observer* observer) { observer_ = observer; }
+  Observer* observer() const { return observer_; }
+
+ private:
+  Observer* observer_ = nullptr;
+  DISALLOW_COPY_AND_ASSIGN(ChooserChoices);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBSITE_SETTINGS_CHOOSER_CHOICES_H_