Add MetalayerMode to the palette.

ash/system/palette/tools/metalayer_mode.h

Index: ash/system/palette/tools/metalayer_mode.h
diff --git a/ash/system/palette/tools/metalayer_mode.h b/ash/system/palette/tools/metalayer_mode.h
new file mode 100644
index 0000000000000000000000000000000000000000..c839fa9192f7f7c2ad2b282299f73df39486923a
--- /dev/null
+++ b/ash/system/palette/tools/metalayer_mode.h
@@ -0,0 +1,42 @@
+// Copyright 2017 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 ASH_SYSTEM_PALETTE_TOOLS_METALAYER_MODE_H_
+#define ASH_SYSTEM_PALETTE_TOOLS_METALAYER_MODE_H_
+
+#include "ash/ash_export.h"
+#include "ash/system/palette/common_palette_tool.h"
+#include "base/memory/weak_ptr.h"
+
+namespace ash {
+
+// A palette tool that lets the user select a screen region to be passed
+// to the voice interaction framework.
+class ASH_EXPORT MetalayerMode : public CommonPaletteTool {
+ public:
+  explicit MetalayerMode(Delegate* delegate);
+  ~MetalayerMode() override;
+
+ private:
+  // PaletteTool:
+  PaletteGroup GetGroup() const override;
+  PaletteToolId GetToolId() const override;
+  void OnEnable() override;
+  void OnDisable() override;
+  const gfx::VectorIcon& GetActiveTrayIcon() const override;
+  views::View* CreateView() override;
+
+  // CommonPaletteTool:
+  const gfx::VectorIcon& GetPaletteIcon() const override;
+
+  void OnMetalayerDone();
+
+  base::WeakPtrFactory<MetalayerMode> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MetalayerMode);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_PALETTE_TOOLS_METALAYER_MODE_H_