Disable 2 flaky content_browsertests on Mac.

content/browser/frame_host/render_frame_host_manager_browsertest.cc

Index: content/browser/frame_host/render_frame_host_manager_browsertest.cc
diff --git a/content/browser/frame_host/render_frame_host_manager_browsertest.cc b/content/browser/frame_host/render_frame_host_manager_browsertest.cc
index 6a4222378aeaa7c278e4e409cf407a77e37ebfba..4de22b09c271d25907397d7acedc5144a040e880 100644
--- a/content/browser/frame_host/render_frame_host_manager_browsertest.cc
+++ b/content/browser/frame_host/render_frame_host_manager_browsertest.cc
@@ -1562,8 +1562,16 @@ class FileChooserDelegate : public WebContentsDelegate {
 };
 
 // Test for http://crbug.com/262948.
+// Flaky on Mac. http://crbug.com/452018
+#if defined(OS_MACOSX)
+#define MAYBE_RestoreFileAccessForHistoryNavigation \
+  DISABLED_RestoreFileAccessForHistoryNavigation
+#else
+#define MAYBE_RestoreFileAccessForHistoryNavigation \
+  RestoreFileAccessForHistoryNavigation
+#endif
 IN_PROC_BROWSER_TEST_F(RenderFrameHostManagerTest,
-                       RestoreFileAccessForHistoryNavigation) {
+                       MAYBE_RestoreFileAccessForHistoryNavigation) {
   StartServer();
   base::FilePath file;
   EXPECT_TRUE(PathService::Get(base::DIR_TEMP, &file));