Add palette tool/manager.

ash/common/system/chromeos/palette/palette_tool.cc

+// Copyright 2016 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/common/system/chromeos/palette/palette_tool.h"
+
+#include "base/logging.h"
+#include "ui/gfx/vector_icons_public.h"
+
+namespace ash {
+
+// static
+void PaletteTool::RegisterToolInstances(PaletteToolManager* tool_manager) {}
+
+PaletteTool::PaletteTool(Delegate* delegate) : delegate_(delegate) {}
+
+PaletteTool::~PaletteTool() {}
+
+void PaletteTool::OnEnable() {
+  enabled_ = true;
+}
+
+void PaletteTool::OnDisable() {
+  enabled_ = false;
+}
+
+gfx::VectorIconId PaletteTool::GetActiveTrayIcon() {
+  return gfx::VectorIconId::VECTOR_ICON_NONE;
+}
+
+}  // namespace ash