Disable flaky SitePerProcessHitTestBrowserTest.InputEventRouterGestureTargetMapTest

BUG=823578
TBR=riajiang@chromium.org,sadrul@chromium.org,kenrb@chromium.org

Change-Id: Id67a578a183ad65a80f9a72f610cf554c164cd12
Reviewed-on: https://chromium-review.googlesource.com/973605
Commit-Queue: Alexander Potapenko <glider@chromium.org>
Reviewed-by: Alexander Potapenko <glider@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544726}

content/browser/site_per_process_hit_test_browsertest.cc

@@ -2452,8 +2452,9 @@ void SendTouchpadFlingSequenceWithExpectedTarget(
 
 }  // anonymous namespace
 
+// Flaky, see https://crbug.com/823578
 IN_PROC_BROWSER_TEST_P(SitePerProcessHitTestBrowserTest,
-                       InputEventRouterGestureTargetMapTest) {
+                       DISABLED_InputEventRouterGestureTargetMapTest) {
   GURL main_url(embedded_test_server()->GetURL(
       "/frame_tree/page_with_positioned_nested_frames.html"));
   EXPECT_TRUE(NavigateToURL(shell(), main_url));