Disable MediaRouterContainerSearch on Win7 (flaky).

Bug: 760288
Change-Id: I79e0c682394236aa4a7d2dcd421680e09abef082
Reviewed-on: https://chromium-review.googlesource.com/663793Reviewed-by: Derek Cheng <imcheng@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501436}

chrome/test/data/webui/media_router/media_router_elements_browsertest.js

@@ -152,8 +152,14 @@ TEST_F('MediaRouterElementsBrowserTest',
   mocha.run();
 });
 
+// This test is flaky on Windows. See https://crbug.com/760288.
+GEN('#if defined(OS_WIN)');
+GEN('#define MAYBE_MediaRouterContainerSearch DISABLED_MediaRouterContainerSearch');
+GEN('#else');
+GEN('#define MAYBE_MediaRouterContainerSearch MediaRouterContainerSearch');
+GEN('#endif');
 TEST_F('MediaRouterElementsBrowserTest',
-    'MediaRouterContainerSearch',
+    'MAYBE_MediaRouterContainerSearch',
     function() {
   media_router_container_search.registerTests();
   mocha.run();