Re-enable WebSocketBrowserTest.SendCloseFrameWhenTabIsClosed

Start running browser test
WebSocketBrowserTest.SendCloseFrameWhenTabIsClosed on Windows
again. This was flaking on the bots 2 years ago but doesn't fail when
run locally. Experimentally re-enable it to see if it is still flaky.

BUG=616958

Change-Id: I2f927e47593ba5e2e2541a4843db37327129792a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2282840Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Reviewed-by: Eric Roman <eroman@chromium.org>
Commit-Queue: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788405}

chrome/browser/net/websocket_browsertest.cc

@@ -194,16 +194,7 @@ IN_PROC_BROWSER_TEST_F(WebSocketBrowserTest, SecureWebSocketSplitRecords) {
   EXPECT_EQ("PASS", WaitAndGetTitle());
 }
 
-// Flaky failing on Win10 only.  http://crbug.com/616958
-#if defined(OS_WIN)
-#define MAYBE_SendCloseFrameWhenTabIsClosed \
-    DISABLED_SendCloseFrameWhenTabIsClosed
-#else
-#define MAYBE_SendCloseFrameWhenTabIsClosed SendCloseFrameWhenTabIsClosed
-#endif
-
-IN_PROC_BROWSER_TEST_F(WebSocketBrowserTest,
-                       MAYBE_SendCloseFrameWhenTabIsClosed) {
+IN_PROC_BROWSER_TEST_F(WebSocketBrowserTest, SendCloseFrameWhenTabIsClosed) {
   // Launch a WebSocket server.
   ASSERT_TRUE(ws_server_.Start());