Disable flaky "PreviewsNoScriptBrowserTest.NoScriptPreviewsEnabledButNoTransformDirective"

This patch disables the browsertest on Win,Mac and Linux.

TBR: dougarnett@chromium.org
Bug: 803626
Change-Id: I9d145603d154cc7316bcb5ddf536417f146df568
Reviewed-on: https://chromium-review.googlesource.com/874986Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530425}

chrome/browser/previews/previews_browsertest.cc

@@ -169,8 +169,16 @@ IN_PROC_BROWSER_TEST_F(PreviewsNoScriptBrowserTest,
   EXPECT_FALSE(noscript_css_requested());
 }
 
+// Flaky in all platforms except Android. See crbug.com/803626 for detail.
+#if defined(OS_ANDROID)
+#define MAYBE_NoScriptPreviewsEnabledButNoTransformDirective \
+  NoScriptPreviewsEnabledButNoTransformDirective
+#else
+#define MAYBE_NoScriptPreviewsEnabledButNoTransformDirective \
+  DISABLED_NoScriptPreviewsEnabledButNoTransformDirective
+#endif
 IN_PROC_BROWSER_TEST_F(PreviewsNoScriptBrowserTest,
-                       NoScriptPreviewsEnabledButNoTransformDirective) {
+                       MAYBE_NoScriptPreviewsEnabledButNoTransformDirective) {
   base::HistogramTester histogram_tester;
   ui_test_utils::NavigateToURL(browser(), https_no_transform_url());