Fix panel showing logic when Chrome enters the fullscreen mode

chrome/browser/ui/cocoa/panels/panel_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_cocoa.h"
 
 #include "base/logging.h"
 #import "chrome/browser/ui/cocoa/chrome_event_processing_window.h"
 #import "chrome/browser/ui/cocoa/panels/panel_titlebar_view_cocoa.h"
 #import "chrome/browser/ui/cocoa/panels/panel_utils_cocoa.h"
@@ skipping 192 matching lines @@
     const NativeWebKeyboardEvent& event) {
   if (event.skip_in_browser || event.type == NativeWebKeyboardEvent::Char)
     return;
 
   ChromeEventProcessingWindow* event_window =
       static_cast<ChromeEventProcessingWindow*>([controller_ window]);
   DCHECK([event_window isKindOfClass:[ChromeEventProcessingWindow class]]);
   [event_window redispatchKeyEvent:event.os_event];
 }
 
-void PanelCocoa::FullScreenModeChanged(
-    bool is_full_screen) {
+void PanelCocoa::FullScreenModeChanged(bool is_full_screen) {
+  if (!is_shown_) {
+    // If the panel window is not shown due to that a Chrome tab window is in
+    // fullscreen mode when the panel is being created, we need to show the
+    // panel window now. In addition, its titlebar needs to be updated since it
+    // is not done at the panel creation time.
+    if (!is_full_screen) {
+      ShowPanelInactive();
+      UpdatePanelTitleBar();
+    }
+
+    // No need to proceed when the panel window was not shown previously.
+    // We either show the panel window or do not show it depending on current
+    // full screen state.
+    return;
+  }
   [controller_ fullScreenModeChanged:is_full_screen];
 }
 
 bool PanelCocoa::IsPanelAlwaysOnTop() const {
   return always_on_top_;
 }
 
 void PanelCocoa::SetPanelAlwaysOnTop(bool on_top) {
   if (always_on_top_ == on_top)
     return;
@@ skipping 175 matching lines @@
       return ![[titlebar() restoreButton] isHidden];
     default:
       NOTREACHED();
   }
   return false;
 }
 
 panel::CornerStyle CocoaNativePanelTesting::GetWindowCornerStyle() const {
   return native_panel_window_->corner_style_;
 }