mediaview: Implement ArcDocumentsProviderRoot.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h

Index: chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
index 07676343ed73aa3662714971567cc1bccc3cf4eb..a0ee76cfe32fb0c073eea49bf47bc024511d97ed 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
+++ b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
@@ -24,6 +24,10 @@ constexpr char kDocumentsProviderMountPointName[] = "arc-documents-provider";
 constexpr base::FilePath::CharType kDocumentsProviderMountPointPath[] =
     "/special/arc-documents-provider";
 
+// MIME type for directories in Android.
+// Defined as DocumentsContract.Document.MIME_TYPE_DIR in Android.
+constexpr char kAndroidDirectoryMimeType[] = "vnd.android.document/directory";
+
 // Parses a FileSystemURL pointing to ARC documents provider file system.
 // On success, true is returned. All arguments must not be nullptr.
 bool ParseDocumentsProviderUrl(const storage::FileSystemURL& url,