Let beacon/keepalive tests leak

Requests with keepalive set (including requests initiated by
sendBeacon()) are leaky by design; they are kept alive even when the
frame is detached. This change makes it explicit in LeakExpectations.

Bug: 755625
Change-Id: I9c708e7f492bb2859bad007faa201e79517f03a2
Reviewed-on: https://chromium-review.googlesource.com/920123
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536967}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -31,15 +31,18 @@ crbug.com/664874 http/tests/xmlhttprequest/workers/xmlhttprequest-allowed-with-d
 crbug.com/672740 http/tests/security/mixedContent/websocket/insecure-websocket-in-secure-page-worker-allowed.html [ Leak Pass ]
 crbug.com/672740 http/tests/security/mixedContent/websocket/insecure-websocket-in-secure-page-worker.html [ Leak Pass ]
 
-crbug.com/755625 external/wpt/beacon/beacon-error.window.html [ Leak ]
-
 crbug.com/786995 virtual/threaded/http/tests/devtools/tracing/timeline-style/timeline-style-recalc-all-invalidator-types.js [ Leak Pass ]
 
+# Requests with keepalive specified will be kept alive even when the frame is
+# detached, which means leaks reported by the leak detector are by design.
+# Ignore them.
+crbug.com/755625 external/wpt/beacon/beacon-error.window.html [ Leak ]
+crbug.com/762353 external/wpt/beacon/headers/header-referrer-no-referrer.html [ Leak ]
+crbug.com/651742 external/wpt/content-security-policy/connect-src/connect-src-beacon-allowed.sub.html [ Leak ]
+
 # -----------------------------------------------------------------
 # Flakily leaks
 # -----------------------------------------------------------------
-crbug.com/762353 external/wpt/beacon/headers/header-referrer-no-referrer.html [ Leak Pass ]
-crbug.com/651742 external/wpt/content-security-policy/connect-src/connect-src-beacon-allowed.sub.html [ Leak Pass ]
 crbug.com/780386 external/wpt/html/dom/reflection-grouping.html [ Leak Pass ]
 crbug.com/796944 [ Linux ] synthetic_gestures/synthetic-pinch-zoom-gesture.html [ Leak Pass ]
 crbug.com/667560 [ Linux ] http/tests/devtools/console/console-search.js [ Leak Pass ]