Fix panel showing logic when Chrome enters the fullscreen mode

chrome/browser/ui/cocoa/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/cocoa/panels/panel_window_controller_cocoa.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 831 matching lines @@
   windowShim_->panel()->OnActiveStateChanged(false);
 }
 
 - (void)preventBecomingKeyWindow:(BOOL)prevent {
   canBecomeKeyWindow_ = !prevent;
 }
 
 - (void)fullScreenModeChanged:(bool)isFullScreen {
   [self updateWindowLevel];
 
-  // The full-screen window is in normal level and changing the panel window to
-  // same normal level will not move it below the full-screen window. Thus we
-  // need to reorder the panel window.
+  // If the panel is not always on top, its z-order should not be affected if
+  // some other window enters fullscreen mode.
+  if (!windowShim_->panel()->IsAlwaysOnTop())
+    return;
+
+  // The full-screen window is in normal level and changing the panel window
+  // to same normal level will not move it below the full-screen window. Thus
+  // we need to reorder the panel window.
   if (isFullScreen)
     [[self window] orderBack:nil];
   else
     [[self window] orderFrontRegardless];
 }
 
 - (BOOL)canBecomeKeyWindow {
   // Panel can only gain focus if it is expanded. Minimized panels do not
   // participate in Cmd-~ rotation.
   // TODO(dimich): If it will be ever desired to expand/focus the Panel on
@@ skipping 66 matching lines @@
 - (NSRect)contentRectForFrameRect:(NSRect)frameRect {
   NSRect contentRect = [[[self window] contentView] convertRect:frameRect
                                                        fromView:nil];
   contentRect.size.height -= panel::kTitlebarHeight;
   if (contentRect.size.height < 0)
     contentRect.size.height = 0;
   return contentRect;
 }
 
 @end