Fix compile warnings in Panel.xib

chrome/browser/ui/panels/panel_window_controller_cocoa.mm

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/ui/panels/panel_window_controller_cocoa.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 57 matching lines @@
 };
 
 #endif  // MAC_OS_X_VERSION_10_6
 
 @interface PanelWindowControllerCocoa (PanelsCanBecomeKey)
 // Internal helper method for extracting the total number of panel windows
 // from the panel manager. Used to decide if panel can become the key window.
 - (int)numPanels;
 @end
 
-@interface PanelWindowCocoaImpl : ChromeBrowserWindow {
-  // Panel windows use a higher priority NSWindowLevel to ensure they are always
-  // visible, causing the OS to prefer panel windows when selecting a window
-  // to make the key window. To counter this preference, we override
-  // -[NSWindow:canBecomeKeyWindow] to restrict when the panel can become the
-  // key window to a limited set of scenarios, such as when cycling through
-  // windows, when panels are the only remaining windows, when an event
-  // triggers window activation, etc. The panel may also be prevented from
-  // becoming the key window, regardless of the above scenarios, such as when
-  // a panel is minimized.
-  BOOL canBecomeKey_;  // Defaults to NO.
-}
-@end
-
 @implementation PanelWindowCocoaImpl
 // The panels cannot be reduced to 3-px windows on the edge of the screen
 // active area (above Dock). Default constraining logic makes at least a height
 // of the titlebar visible, so the user could still grab it. We do 'restore'
 // differently, and minimize panels to 3 px. Hence the need to override the
 // constraining logic.
 - (NSRect)constrainFrameRect:(NSRect)frameRect toScreen:(NSScreen *)screen {
   return frameRect;
 }
 
@@ skipping 972 matching lines @@
   if (![self isWindowLoaded])
     return;
   [[self window] invalidateCursorRectsForView:overlayView_];
 }
 
 - (BOOL)isActivationByClickingTitlebarEnabled {
   return !windowShim_->panel()->always_on_top();
 }
 
 @end