Re-enable all GalleryBrowserTestInGuestMode browser tests

Re-enable all GalleryBrowserTestInGuestMode tests, listed below, which
were disabled in issue 804413 due to linux-chromeos-release bot flakes
on the CQ. (Guest mode RenameImageOnDownloads disabled on issue 508949
before issue 804413).

  GalleryBrowserTestInGuestMode.RenameImageOnDownloads
  GalleryBrowserTestInGuestMode.
      CheckAvailabilityOfShareButtonOnDownloads
  GalleryBrowserTestInGuestMode.ResizeImageOnDownloads

Bug: 804413, 508949
Change-Id: I254a9597c7fdd727cfb888db4c552cc3ad67b0a6
Reviewed-on: https://chromium-review.googlesource.com/992592Reviewed-by: Sasha Morrissey <sashab@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547972}

chrome/browser/chromeos/file_manager/gallery_browsertest.cc

@@ -170,14 +170,7 @@ IN_PROC_BROWSER_TEST_F(GalleryBrowserTest, DISABLED_RenameImageOnDownloads) {
   StartTest();
 }
 
-// http://crbug.com/508949
-#if defined(MEMORY_SANITIZER)
-#define MAYBE_RenameImageOnDownloads DISABLED_RenameImageOnDownloads
-#else
-#define MAYBE_RenameImageOnDownloads RenameImageOnDownloads
-#endif
-IN_PROC_BROWSER_TEST_F(GalleryBrowserTestInGuestMode,
-                       MAYBE_RenameImageOnDownloads) {
+IN_PROC_BROWSER_TEST_F(GalleryBrowserTestInGuestMode, RenameImageOnDownloads) {
   set_test_case_name("renameImageOnDownloads");
   StartTest();
 }
@@ -233,7 +226,7 @@ IN_PROC_BROWSER_TEST_F(GalleryBrowserTest,
 }
 
 IN_PROC_BROWSER_TEST_F(GalleryBrowserTestInGuestMode,
-                       MAYBE_CheckAvailabilityOfShareButtonOnDownloads) {
+                       CheckAvailabilityOfShareButtonOnDownloads) {
   set_test_case_name("checkAvailabilityOfShareButtonOnDownloads");
   StartTest();
 }
@@ -343,8 +336,7 @@ IN_PROC_BROWSER_TEST_F(GalleryBrowserTest, MAYBE_ResizeImageOnDownloads) {
   StartTest();
 }
 
-IN_PROC_BROWSER_TEST_F(GalleryBrowserTestInGuestMode,
-                       MAYBE_ResizeImageOnDownloads) {
+IN_PROC_BROWSER_TEST_F(GalleryBrowserTestInGuestMode, ResizeImageOnDownloads) {
   set_test_case_name("resizeImageOnDownloads");
   StartTest();
 }