media: add video capture device for ARC++ camera HAL v3

media/capture/video/chromeos/camera_metadata_utils.h

+// 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.
+
+#include "media/capture/video/chromeos/mojo/arc_camera3_metadata.mojom.h"
+
+namespace media {
+
+const arc::mojom::CameraMetadataEntryPtr* GetMetadataEntry(
+    const arc::mojom::CameraMetadataPtr& camera_metadata,
+    arc::mojom::CameraMetadataTag tag);
+
+void MergeMetadata(arc::mojom::CameraMetadataPtr* to,
+                   const arc::mojom::CameraMetadataPtr& from);
+
+}  // namespace media