Add a media scanner convenience class.

chrome/browser/chromeos/file_manager/file_manager_jstest.cc

Index: chrome/browser/chromeos/file_manager/file_manager_jstest.cc
diff --git a/chrome/browser/chromeos/file_manager/file_manager_jstest.cc b/chrome/browser/chromeos/file_manager/file_manager_jstest.cc
index 6d6a4e2b0f43f2a6ab39f12c0172d0438ebffecd..fcc4fb0d694ef725d1d3a9785f416d10f8c5ba06 100644
--- a/chrome/browser/chromeos/file_manager/file_manager_jstest.cc
+++ b/chrome/browser/chromeos/file_manager/file_manager_jstest.cc
@@ -75,3 +75,8 @@ IN_PROC_BROWSER_TEST_F(FileManagerJsTest, DirectoryTreeTest) {
   RunTest(base::FilePath(
       FILE_PATH_LITERAL("directory_tree_unittest.html")));
 }
+
+IN_PROC_BROWSER_TEST_F(FileManagerJsTest, MediaScannerTest) {
+  RunTest(base::FilePath(
+      FILE_PATH_LITERAL("media_scanner_unittest.html")));
+}