Disable SiteDetailsBrowserTest.IsolateExtensions on Mac

chrome/browser/site_details_browsertest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/site_details.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 640 matching lines @@
                   "SiteIsolation.ProxyCountPerBrowsingInstance"),
               DependingOnPolicy(
                   ElementsAre(Bucket(0, 3)), ElementsAre(Bucket(0, 3)),
                   ElementsAre(Bucket(12, 1), Bucket(29, 1), Bucket(68, 1))));
 
   // This test doesn't navigate to any extensions URLs, so it should not be
   // in any of the field trial groups.
   EXPECT_FALSE(IsInTrial("SiteIsolationExtensionsActive"));
 }
 
-// Flaky on Windows. crbug.com/671891
-#if defined(OS_WIN)
+// Flaky on Windows and Mac. crbug.com/671891
+#if defined(OS_WIN) || defined(OS_MACOSX)
 #define MAYBE_IsolateExtensions DISABLED_IsolateExtensions
 #else
 #define MAYBE_IsolateExtensions IsolateExtensions
 #endif
 IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, MAYBE_IsolateExtensions) {
   // We start on "about:blank", which should be credited with a process in this
   // case.
   scoped_refptr<TestMemoryDetails> details = new TestMemoryDetails();
   details->StartFetchAndWait();
   EXPECT_THAT(details->uma()->GetAllSamples(
@@ skipping 622 matching lines @@
   content::NavigateIframeToURL(
       tab, "child-1", extension2->GetResourceURL("/blank_iframe.html"));
   details = new TestMemoryDetails();
   details->StartFetchAndWait();
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.SiteInstancesPerBrowsingInstance"),
               DependingOnPolicy(ElementsAre(Bucket(1, 2)),
                                 ElementsAre(Bucket(1, 1), Bucket(3, 1)),
                                 ElementsAre(Bucket(1, 1), Bucket(5, 1))));
 }