Revert "[Sheriff] Disable SingleProcessBrowserTest.Test on Win."

This reverts commit 2a6e4af1.

Reason for revert: The test should no longer be flaky on Windows.

Original change's description:
> [Sheriff] Disable SingleProcessBrowserTest.Test on Win.
> 
> Flaky.
> 
> TBR=rockot@google.com
> 
> Bug: 987448
> Change-Id: I6db59e7ce6ac618320e10bfe85b1aa700e0fbce1
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1730902
> Reviewed-by: vitaliii <vitaliii@chromium.org>
> Commit-Queue: vitaliii <vitaliii@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#683173}

TBR=rockot@google.com,vitaliii@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 987448
Change-Id: Ia37df33292f76bf965d07da3168933586e564061
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1736439Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#684053}

chrome/test/base/in_process_browser_test_browsertest.cc

@@ -105,9 +105,8 @@ class SingleProcessBrowserTest : public InProcessBrowserTest {
   }
 };
 
-#if defined(OS_LINUX) || defined(OS_WIN)
-// TODO(https://crbug.com/931233): Reenable on Linux.
-// TODO(https://crbug.com/987448): Reenable on Windows.
+#if defined(OS_LINUX)
+// TODO(https://crbug.com/931233): Reenable
 #define MAYBE_Test DISABLED_Test
 #else
 #define MAYBE_Test Test