Re-commit "win: Set is_clang=true by default" over the weekend.

chrome/browser/prerender/prerender_browsertest.cc

Index: chrome/browser/prerender/prerender_browsertest.cc
diff --git a/chrome/browser/prerender/prerender_browsertest.cc b/chrome/browser/prerender/prerender_browsertest.cc
index 0c6d628ea0be1864673052f8f84385b859af7774..840f7ef8541ed5fd943454aff262a53caf6c02d0 100644
--- a/chrome/browser/prerender/prerender_browsertest.cc
+++ b/chrome/browser/prerender/prerender_browsertest.cc
@@ -2009,6 +2009,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderWindowSize) {
 // TODO(jam): http://crbug.com/350550
 #if !(defined(OS_CHROMEOS) && defined(ADDRESS_SANITIZER))
 
+// TODO(hans): Temporarily disable while enabling Clang by default on Windows
+// over the weekend. (crbug.com/727458)
+#if !(defined(OS_WIN) && defined(__clang__))
+
 // Checks that prerenderers will terminate when the RenderView crashes.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderRendererCrash) {
   std::unique_ptr<TestPrerender> prerender = PrerenderTestURL(
@@ -2026,6 +2030,7 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderRendererCrash) {
   prerender->WaitForStop();
 }
 #endif
+#endif
 
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        PrerenderPageWithFragment) {