Mark ExtensionApiTest.CrossOriginXHRFileAccess flaky on Mac.

chrome/browser/extensions/cross_origin_xhr_apitest.cc

Index: chrome/browser/extensions/cross_origin_xhr_apitest.cc
diff --git a/chrome/browser/extensions/cross_origin_xhr_apitest.cc b/chrome/browser/extensions/cross_origin_xhr_apitest.cc
index 7f678976e16ae4dce851dfd172c452a60584d476..790901965fc702ffffaf3e0ae9d00b04b1bda8fc 100644
--- a/chrome/browser/extensions/cross_origin_xhr_apitest.cc
+++ b/chrome/browser/extensions/cross_origin_xhr_apitest.cc
@@ -23,7 +23,14 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, CrossOriginXHRContentScript) {
   ASSERT_TRUE(RunExtensionTest("cross_origin_xhr/content_script")) << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(ExtensionApiTest, CrossOriginXHRFileAccess) {
+// Flaky on Mac 10.5, crbug.com/105179.
+#if defined(OS_MACOSX)
+#define MAYBE_CrossOriginXHRFileAccess FLAKY_CrossOriginXHRFileAccess
+#else
+#define MAYBE_CrossOriginXHRFileAccess CrossOriginXHRFileAccess
+#endif
+
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, MAYBE_CrossOriginXHRFileAccess) {
   ASSERT_TRUE(RunExtensionTest("cross_origin_xhr/file_access")) << message_;
 }