Convert TrayBubbleView to wm common types

ui/views/bubble/bubble_dialog_delegate.h

 // Copyright 2016 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 UI_VIEWS_BUBBLE_BUBBLE_DIALOG_DELEGATE_H_
 #define UI_VIEWS_BUBBLE_BUBBLE_DIALOG_DELEGATE_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/views/bubble/bubble_border.h"
@@ skipping 81 matching lines @@
   bool border_accepts_events() const { return border_accepts_events_; }
   void set_border_accepts_events(bool event) { border_accepts_events_ = event; }
 
   bool adjust_if_offscreen() const { return adjust_if_offscreen_; }
   void set_adjust_if_offscreen(bool adjust) { adjust_if_offscreen_ = adjust; }
 
   // Get the arrow's anchor rect in screen space.
   virtual gfx::Rect GetAnchorRect() const;
 
   // Allows delegates to provide custom parameters before widget initialization.
+  // For example, mus needs to set a custom mus::Window* parent.
   virtual void OnBeforeBubbleWidgetInit(Widget::InitParams* params,
                                         Widget* widget) const;
 
   // Sets |margins_| to a default picked for smaller bubbles.
   void UseCompactMargins();
 
   // Sets the bubble alignment relative to the anchor. This may only be called
   // after calling CreateBubble.
   void SetAlignment(BubbleBorder::BubbleAlignment alignment);
 
@@ skipping 88 matching lines @@
 
   // Parent native window of the bubble.
   gfx::NativeView parent_window_;
 
   DISALLOW_COPY_AND_ASSIGN(BubbleDialogDelegateView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_BUBBLE_BUBBLE_DELEGATE2_H_