Add generic PaletteDelegate code.

ash/test/test_shell_delegate.cc

 // 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 "ash/test/test_shell_delegate.h"
 
 #include <limits>
 
 #include "ash/app_list/app_list_presenter_delegate.h"
 #include "ash/app_list/app_list_presenter_delegate_factory.h"
@@ skipping 168 matching lines @@
 }
 
 NewWindowDelegate* TestShellDelegate::CreateNewWindowDelegate() {
   return new NewWindowDelegateImpl;
 }
 
 MediaDelegate* TestShellDelegate::CreateMediaDelegate() {
   return new MediaDelegateImpl;
 }
 
+PaletteDelegate* TestShellDelegate::CreatePaletteDelegate() {
+  return nullptr;
+}
+
 std::unique_ptr<PointerWatcherDelegate>
 TestShellDelegate::CreatePointerWatcherDelegate() {
   return base::WrapUnique(new PointerWatcherDelegateAura);
 }
 
 ui::MenuModel* TestShellDelegate::CreateContextMenu(WmShelf* wm_shelf,
                                                     const ShelfItem* item) {
   return nullptr;
 }
 
@@ skipping 13 matching lines @@
 void TestShellDelegate::SetMediaCaptureState(MediaCaptureState state) {
 #if defined(OS_CHROMEOS)
   static_cast<MediaDelegateImpl*>(WmShell::Get()->media_delegate())
       ->set_media_capture_state(state);
   WmShell::Get()->system_tray_notifier()->NotifyMediaCaptureChanged();
 #endif
 }
 
 }  // namespace test
 }  // namespace ash