Disabled the failed test MediaGalleriesPlatformAppBrowserTest.GetMetadata.

chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc

 // Copyright (c) 2012 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.
 
 #include <stdint.h>
 
 #include "base/auto_reset.h"
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 430 matching lines @@
   MakeSingleFakeGallery(&pref_id);
 
   base::ListValue custom_args;
   custom_args.AppendInteger(base::checked_cast<int>(pref_id));
   custom_args.AppendString(
       browser()->profile()->GetPath().BaseName().MaybeAsASCII());
 
   ASSERT_TRUE(RunMediaGalleriesTestWithArg("tourl", custom_args)) << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(MediaGalleriesPlatformAppBrowserTest, GetMetadata) {
+// The test failed continuosly on linux_ChromeOS. Disable it until the root
+// cause if fixed. crbug.com/618121.
+IN_PROC_BROWSER_TEST_F(MediaGalleriesPlatformAppBrowserTest,
+                       DISABLED_GetMetadata) {
   RemoveAllGalleries();
   MakeSingleFakeGallery(NULL);
 
   AddFileToSingleFakeGallery(media::GetTestDataFilePath("90rotation.mp4"));
   AddFileToSingleFakeGallery(media::GetTestDataFilePath("id3_png_test.mp3"));
 
   base::ListValue custom_args;
 #if defined(USE_PROPRIETARY_CODECS)
   custom_args.AppendBoolean(true);
 #else
   custom_args.AppendBoolean(false);
 #endif
   ASSERT_TRUE(RunMediaGalleriesTestWithArg("media_metadata", custom_args))
       << message_;
 }