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 1d4f263da7e0e57088b24ac0e2c51fdce6f07333..87d6b9a96c650f522fe2c1c89007e6964e54b94c 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
+++ b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h
@@ -23,6 +23,10 @@ extern const char kDocumentsProviderMountPointName[];
 // The path of ARC documents provider file system mount point.
 extern const base::FilePath::CharType kDocumentsProviderMountPointPath[];
 
+// MIME type for directories in Android.
+// Defined as DocumentsContract.Document.MIME_TYPE_DIR in Android.
+extern const char kAndroidDirectoryMimeType[];
+
 // 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,