arc: Add URL converter functions

chrome/browser/chromeos/fileapi/external_file_url_util.cc

Index: chrome/browser/chromeos/fileapi/external_file_url_util.cc
diff --git a/chrome/browser/chromeos/fileapi/external_file_url_util.cc b/chrome/browser/chromeos/fileapi/external_file_url_util.cc
index 74910d722cc2584c3509efc299e1cebecbd2e109..42c7e3d34e30e5e8e371be772251c056d79f6c05 100644
--- a/chrome/browser/chromeos/fileapi/external_file_url_util.cc
+++ b/chrome/browser/chromeos/fileapi/external_file_url_util.cc
@@ -37,10 +37,7 @@ GURL FileSystemURLToExternalFileURL(
     return GURL();
   }
 
-  return GURL(base::StringPrintf(
-      "%s:%s",
-      content::kExternalFileScheme,
-      file_system_url.virtual_path().AsUTF8Unsafe().c_str()));
+  return VirtualPathToExternalFileURL(file_system_url.virtual_path());
 }
 
 base::FilePath ExternalFileURLToVirtualPath(const GURL& url) {
@@ -51,6 +48,11 @@ base::FilePath ExternalFileURLToVirtualPath(const GURL& url) {
   return base::FilePath::FromUTF8Unsafe(path_string);
 }
 
+GURL VirtualPathToExternalFileURL(const base::FilePath& virtual_path) {
+  return GURL(base::StringPrintf("%s:%s", content::kExternalFileScheme,
+                                 virtual_path.AsUTF8Unsafe().c_str()));
+}
+
 GURL CreateExternalFileURLFromPath(Profile* profile,
                                    const base::FilePath& path) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);