Make PanelBrowserView derive from NativePanel. Also add some more methods to NativePanel.

chrome/browser/ui/panels/native_panel.h

Index: chrome/browser/ui/panels/native_panel.h
===================================================================
--- chrome/browser/ui/panels/native_panel.h	(revision 88351)
+++ chrome/browser/ui/panels/native_panel.h	(working copy)
@@ -6,6 +6,8 @@
 #define CHROME_BROWSER_UI_PANELS_NATIVE_PANEL_H_
 #pragma once
 
+#include "ui/gfx/native_widget_types.h"
+
 namespace gfx {
 class Rect;
 }  // namespace gfx
@@ -28,9 +30,14 @@
   virtual void RestorePanel() = 0;
   virtual void ClosePanel() = 0;
   virtual void ActivatePanel() = 0;
-  virtual void DeactivePanel() = 0;
-  virtual bool IsActivePanel() const = 0;
+  virtual void DeactivatePanel() = 0;
+  virtual bool IsPanelActive() const = 0;
+  virtual gfx::NativeWindow GetNativePanelHandle() = 0;
+  virtual void UpdatePanelTitleBar() = 0;
+  virtual void ShowTaskManagerForPanel() = 0;
+  virtual void NotifyPanelOnUserChangedTheme() = 0;
   virtual void FlashPanelFrame() = 0;
+  virtual void DestroyPanelBrowser() = 0;
 
  protected:
   virtual ~NativePanel() {}