Disabled the failed test MediaGalleriesPlatformAppBrowserTest.GetMetadata.

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

Index: chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc
diff --git a/chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc b/chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc
index e51dd4355882b08b6758bf4be30213a87bf65c76..8368a79e2d1f507bf23a2907567137d7672983d3 100644
--- a/chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc
+++ b/chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc
@@ -448,7 +448,10 @@ IN_PROC_BROWSER_TEST_F(MediaGalleriesPlatformAppBrowserTest, ToURL) {
   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);