Disable DisplayLockingAll test on Win and Linux

The test is flaky on Win and Linux:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyVAsSBUZsYWtlIkljaHJvbWl1bUBjb250ZW50X2Jyb3dzZXJ0ZXN0c0BEdW1wQWNjZXNzaWJpbGl0eVRyZWVUZXN0LkRpc3BsYXlMb2NraW5nQWxsDA

TBR=rakina@chromium.org

Bug: 1043480
Change-Id: Ibaf32c82c5f823717a587c8377aa9484a2b8b803
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2023480Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736027}

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

@@ -2266,7 +2266,13 @@ IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
   RunDisplayLockingTest(FILE_PATH_LITERAL("non-activatable.html"));
 }
 
-IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest, DisplayLockingAll) {
+#if defined(OS_WIN) || defined(OS_LINUX)
+// The test is flaky on Win and Linux. crbug.com/1043480.
+#define MAYBE_DisplayLockingAll DISABLED_DisplayLockingAll
+#else
+#define MAYBE_DisplayLockingAll DisplayLockingAll
+#endif
+IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest, MAYBE_DisplayLockingAll) {
   RunDisplayLockingTest(FILE_PATH_LITERAL("all.html"));
 }