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

media/capture/video/chromeos/mojo/arc_camera3_metadata.mojom

+// 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.
+
+module arc.mojom;
+
+import "camera_metadata_tags.mojom";
+
+enum EntryType {
+  TYPE_BYTE = 0,
+  TYPE_INT32 = 1,
+  TYPE_FLOAT = 2,
+  TYPE_INT64 = 3,
+  TYPE_DOUBLE = 4,
+  TYPE_RATIONAL = 5,
+  NUM_TYPES
+};
+
+struct CameraMetadataRational {
+  int32 numerator;
+  int32 denominator;
+};
+
+struct CameraMetadataEntry {
+  uint32 index;
+  CameraMetadataTag tag;
+  EntryType type;
+  uint32 count;
+  array<uint8> data;
+};
+
+struct CameraMetadata {
+  uint32 size;
+  uint32 entry_count;
+  uint32 entry_capacity;
+  uint32 data_count;
+  uint32 data_capacity;
+  array<CameraMetadataEntry>? entries;
+};