Disable flaky SiteDetailsBrowserTest.IsolateExtensions on Windows

chrome/browser/site_details_browsertest.cc

Index: chrome/browser/site_details_browsertest.cc
diff --git a/chrome/browser/site_details_browsertest.cc b/chrome/browser/site_details_browsertest.cc
index a43f5243a0b58decdde9501fe4d76a932363a59b..c5b1cf1f770dab0ec1290e0ba86e74a825e3e330 100644
--- a/chrome/browser/site_details_browsertest.cc
+++ b/chrome/browser/site_details_browsertest.cc
@@ -656,7 +656,13 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyIframes) {
   EXPECT_FALSE(IsInTrial("SiteIsolationExtensionsActive"));
 }
 
-IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, IsolateExtensions) {
+// Flaky on Windows. crbug.com/671891
+#if defined(OS_WIN)
+#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();