Disable flaky Cart tests on Chromeos.

Bug: 1257964
Change-Id: Iebd00b1cbdb3c5adcc0abd29281822917b0e803a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3216065
Reviewed-by: Nic Hollingum <hollingum@google.com>
Reviewed-by: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Owners-Override: Nic Hollingum <hollingum@google.com>
Auto-Submit: Nic Hollingum <hollingum@google.com>
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#930017}

chrome/renderer/cart/commerce_hint_agent_browsertest.cc

@@ -824,8 +824,8 @@ class CommerceHintTimeoutTest : public CommerceHintAgentTest {
   base::test::ScopedFeatureList scoped_feature_list_;
 };
 
-// Flaky on Linux: https://crbug.com/1257964.
-#if defined(OS_LINUX)
+// Flaky on Linux and ChromeOS: https://crbug.com/1257964.
+#if defined(OS_LINUX) || defined(OS_CHROMEOS)
 #define MAYBE_ExtractCart DISABLED_ExtractCart
 #else
 #define MAYBE_ExtractCart ExtractCart