Disable GalleryBrowserTest.CheckAvailabilityOfEditAndPrintButtons

Flakes in RELEASE on linux-chromeos-rel CQ bot.

Tbr: tapted
Bug: 850372,857021
Change-Id: I548307fa8a93689a348f2e96504815e3fe27cf44
Reviewed-on: https://chromium-review.googlesource.com/1116879Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570745}

chrome/browser/chromeos/file_manager/gallery_browsertest.cc

@@ -71,8 +71,9 @@ IN_PROC_BROWSER_TEST_F(GalleryBrowserTest, OpenMultipleImagesOnDrive) {
   StartTest();
 }
 
+// Flaky in RELEASE crbug.com/857021
 IN_PROC_BROWSER_TEST_F(GalleryBrowserTest,
-                       CheckAvailabilityOfEditAndPrintButtons) {
+                       DISABLED_CheckAvailabilityOfEditAndPrintButtons) {
   set_test_case_name("checkAvailabilityOfEditAndPrintButtons");
   StartTest();
 }