Change the visual appearance of panel on GTK per new UI design.

chrome/browser/ui/gtk/browser_titlebar_base.h

Index: chrome/browser/ui/gtk/browser_titlebar_base.h
diff --git a/chrome/browser/ui/gtk/browser_titlebar_base.h b/chrome/browser/ui/gtk/browser_titlebar_base.h
new file mode 100644
index 0000000000000000000000000000000000000000..f8c8843015117070b7ebaff962b439583f5ec15d
--- /dev/null
+++ b/chrome/browser/ui/gtk/browser_titlebar_base.h
@@ -0,0 +1,50 @@
+// 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.
+
+#ifndef CHROME_BROWSER_UI_GTK_BROWSER_TITLEBAR_BASE_H_
+#define CHROME_BROWSER_UI_GTK_BROWSER_TITLEBAR_BASE_H_
+#pragma once
+
+#include <gtk/gtk.h>
+
+#include "base/compiler_specific.h"
+
+class AvatarMenuButtonGtk;
+
+namespace content {
+class WebContents;
+}
+
+class BrowserTitlebarBase {
+ public:
+  virtual ~BrowserTitlebarBase() { }
+
+  // Build the titlebar, the space above the tab strip, and (maybe) the min,
+  // max, close buttons.
+  virtual void Init() = 0;
+
+  // Updates the title and icon when in app or popup/panel mode (no tabstrip).
+  virtual void UpdateTitleAndIcon() = 0;
+
+  // Update the appearance of the title bar based on whether we're showing a
+  // custom frame or not.  If |use_custom_frame| is true, we show an extra
+  // tall titlebar and the min/max/close buttons.
+  virtual void UpdateCustomFrame(bool use_custom_frame) = 0;
+
+  // Called by the browser asking us to update the loading throbber.
+  // |web_contents| is the tab that is associated with the window throbber.
+  // |web_contents| can be null.
+  virtual void UpdateThrobber(content::WebContents* web_contents) = 0;
+
+  // On Windows, right clicking in the titlebar background brings up the system
+  // menu.  There's no such thing on linux, so we just show the menu items we
+  // add to the menu.
+  virtual void ShowContextMenu(GdkEventButton* event) = 0;
+
+  virtual GtkWidget* widget() const = 0;
+  virtual void set_window(GtkWindow* window) = 0;
+  virtual AvatarMenuButtonGtk* avatar_button() const = 0;
+};
+
+#endif  // CHROME_BROWSER_UI_GTK_BROWSER_TITLEBAR_BASE_H_