Created new PanelStrip base class and make DockedPanelStrip and OverflowPanelStrip its subclasses.

chrome/browser/ui/panels/panel_strip.cc

Index: chrome/browser/ui/panels/panel_strip.cc
diff --git a/chrome/browser/ui/panels/panel_strip.cc b/chrome/browser/ui/panels/panel_strip.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cb88a697542ed60ebc2602d5310be1271a9b216a
--- /dev/null
+++ b/chrome/browser/ui/panels/panel_strip.cc
@@ -0,0 +1,12 @@
+// 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_strip.h"
+
+PanelStrip::PanelStrip(Type type)
+    : type_(type) {
+}
+
+PanelStrip::~PanelStrip() {
+}