Enable the test CancelRequestAfterReadyToCommit.

This test has been disabled on Windows with NavigationMojoResponse:
https://chromium-review.googlesource.com/c/chromium/src/+/958904

Then the issue has been fixed by:
https://chromium-review.googlesource.com/998873

This CL enabled this test again.

Bug: 804868
Change-Id: I77f5faaba1dd6a2e3517fe3d14df5d281a2f5e30
Reviewed-on: https://chromium-review.googlesource.com/1005347Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549548}

content/browser/browser_side_navigation_browsertest.cc

@@ -596,13 +596,6 @@ IN_PROC_BROWSER_TEST_F(BrowserSideNavigationBaseBrowserTest,
 // properly.
 IN_PROC_BROWSER_TEST_F(BrowserSideNavigationBaseBrowserTest,
                        CancelRequestAfterReadyToCommit) {
-// TODO(https://crbug.com/820959). Test temporarily disabled on Windows with
-// NavigationMojoResponse.
-#if defined(OS_WIN)
-  if (IsNavigationMojoResponseEnabled())
-    return;
-#endif
-
   // This test cancels the request using the ResourceDispatchHost. With the
   // NetworkService, it is not used so the request is not canceled.
   // TODO(arthursonzogni): Find a way to cancel a request from the browser