Disabling flaky TabCapture test on Linux and ChromeOS

TBR=miu@chromium.org
BUG=895120

Change-Id: Ic09e5a5721400d1c595d4b2414b5034792793ddf
Reviewed-on: https://chromium-review.googlesource.com/c/1291771Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601209}

chrome/browser/extensions/api/tab_capture/tab_capture_apitest.cc

@@ -221,6 +221,9 @@ IN_PROC_BROWSER_TEST_F(TabCaptureApiPixelTest, OffscreenTabEndToEnd) {
 #if defined(OS_MACOSX)
 // Timeout on Mac. crbug.com/864250
 #define MAYBE_OffscreenTabEvilTests DISABLED_OffscreenTabEvilTests
+#elif defined(OS_LINUX) || defined(OS_CHROMEOS)
+// Flaky on Linux and ChromeOS. crbug.com/895120
+#define MAYBE_OffscreenTabEvilTests DISABLED_OffscreenTabEvilTests
 #else
 #define MAYBE_OffscreenTabEvilTests OffscreenTabEvilTests
 #endif