Disable LaunchWebAuthFlowFunctionTest.UserCloseWindow for flakiness.

The test fails frequently in Linux Tests.

TBR=msarda@chromium.org

Bug: 831848
Change-Id: Ic180e7dfba538cba90737d2b66ee429c9cd97484
Reviewed-on: https://chromium-review.googlesource.com/1008829Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Commit-Queue: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550132}

chrome/browser/extensions/api/identity/identity_apitest.cc

@@ -2096,7 +2096,14 @@ class LaunchWebAuthFlowFunctionTest : public AsyncExtensionBrowserTest {
   }
 };
 
-IN_PROC_BROWSER_TEST_F(LaunchWebAuthFlowFunctionTest, UserCloseWindow) {
+#if defined(OS_LINUX)
+// This test times out on Linux MSan Tests.
+// See https://crbug.com/831848 .
+#define MAYBE_UserCloseWindow DISABLED_UserCloseWindow
+#else
+#define MAYBE_UserCloseWindow UserCloseWindow
+#endif
+IN_PROC_BROWSER_TEST_F(LaunchWebAuthFlowFunctionTest, MAYBE_UserCloseWindow) {
   net::EmbeddedTestServer https_server(net::EmbeddedTestServer::TYPE_HTTPS);
   https_server.ServeFilesFromSourceDirectory(
       "chrome/test/data/extensions/api_test/identity");