Disable ExtensionWebRequestApiTest.WebRequestExtraHeaders on Windows too.

TBR=rdevlin.cronin@chromium.org

Bug: 1003661
Change-Id: I1d921dcf979ba9956bce1553c8f3a3bd2235dbf9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2062353Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742180}

chrome/browser/extensions/api/web_request/web_request_apitest.cc

@@ -611,14 +611,9 @@ IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
       << message_;
 }
 
-// Flaky on multiple platforms: https://crbug.com/1003661
-#if defined(OS_CHROMEOS) || defined(OS_LINUX) || defined(OS_MACOSX)
-#define MAYBE_WebRequestExtraHeaders DISABLED_WebRequestExtraHeaders
-#else
-#define MAYBE_WebRequestExtraHeaders WebRequestExtraHeaders
-#endif
+// Flaky on all platforms: https://crbug.com/1003661
 IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
-                       MAYBE_WebRequestExtraHeaders) {
+                       DISABLED_WebRequestExtraHeaders) {
   CancelLoginDialog login_dialog_helper;
 
   ASSERT_TRUE(StartEmbeddedTestServer());