Add chrome side webusb permission UI code

chrome/browser/ui/website_settings/chooser_bubble_delegate.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_BUBBLE_DELEGATE_H_
+#define CHROME_BROWSER_UI_WEBSITE_SETTINGS_CHOOSER_BUBBLE_DELEGATE_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "base/strings/string16.h"
+#include "components/bubble/bubble_delegate.h"
+
+// Subclass ChooserBubbleDelegate to implement a chooser bubble, which has
+// some introductory text and a list of options that users can pick one of.
+// Create an instance of your subclass and pass it to
+// BubbleManager::ShowBubble() to show the bubble. Your subclass must define
+// the set of options users can pick from; the actions taken after users
+// select an item or press the 'Cancel' button or the bubble is closed.
+// You can also override GetName() to xyz.

[Jeffrey Yasskin, 2015/12/08 20:19:09]

You have to read the comments I suggest and make sure they're correct. Here,
'xyz' was a placeholder for your own explanation.

[juncai, 2015/12/08 20:59:02]

Done.

+// After Select/Cancel/Close is called, this object is destroyed and call back
+// into it is not allowed.
+class ChooserBubbleDelegate : public BubbleDelegate {
+ public:
+  ChooserBubbleDelegate();
+  ~ChooserBubbleDelegate() override;
+
+  // Since the set of options can change while the UI is visible an
+  // implementation should register an observer.
+  class Observer {
+   public:
+    // Called after the options list is initialized for the first time.
+    // OnOptionsInitialized should only be called once.
+    virtual void OnOptionsInitialized() = 0;
+    // Called after GetOptions()[index] has been added to the options and the
+    // newly added option is the last element in the options list. Calling
+    // GetOptions()[index] from inside a call to OnOptionAdded will see the
+    // added string since the options have already been updated.
+    virtual void OnOptionAdded(int index) = 0;
+    // Called when GetOptions()[index] is no longer present, and all later
+    // options have been moved earlier by 1 slot. Calling GetOptions()[index]
+    // from inside a call to OnOptionRemoved will NOT see the removed string
+    // since the options have already been updated.
+    virtual void OnOptionRemoved(int index) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  // BubbleDelegate:
+  std::string GetName() const override;
+
+  // The set of options users can pick from. For example, it can be
+  // USB/Bluetooth devices names which are listed in the chooser bubble
+  // so that users can grant permission.
+  virtual const std::vector<base::string16>& GetOptions() const = 0;
+
+  // These three functions are called just before this object is destroyed:
+  // Called when the user selects the |index|th element from the dialog.
+  virtual void Select(int index) = 0;
+  // Called when the user presses the 'Cancel' button in the dialog.
+  virtual void Cancel() = 0;
+  // Called when the user clicks outside the dialog or the dialog otherwise
+  // closes without the user taking an explicit action.
+  virtual void Close() = 0;
+
+  // Only one observer may be registered at a time.
+  void set_observer(Observer* observer) { observer_ = observer; }
+  Observer* observer() const { return observer_; }
+
+ private:
+  Observer* observer_ = nullptr;
+
+  DISALLOW_COPY_AND_ASSIGN(ChooserBubbleDelegate);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBSITE_SETTINGS_CHOOSER_BUBBLE_DELEGATE_H_