The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4b3f1a993bb370e07a7679d119fc511cfb5cbb51

commit 4b3f1a993bb370e07a7679d119fc511cfb5cbb51
Author: tdresser <tdresser@chromium.org>
Date: Fri May 19 21:38:47 2017

Input Latency traced correctly for mouse events.

Previously, in the case where no swap was produced, we didn't
terminate mouse event async slices. Now we do.

This requires making some of the events blocking, as we need to know whether or not renderering was scheduled at the time we process the event ack. If the event is non-blocking, we receive a synthetic ACK immediately, and don't know whether or not rendering will be scheduled.

BUG= 722807 

Review-Url: https://codereview.chromium.org/2884953002
Cr-Commit-Position: refs/heads/master@{#473334}

[modify] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/content/browser/renderer_host/input/input_router_impl.cc
[modify] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/content/browser/renderer_host/input/input_router_impl.h
[modify] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/content/browser/renderer_host/input/input_router_impl_unittest.cc
[add] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/content/browser/renderer_host/input/mouse_latency_browsertest.cc
[modify] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/content/test/BUILD.gn
[modify] https://crrev.com/4b3f1a993bb370e07a7679d119fc511cfb5cbb51/ui/events/blink/web_input_event_traits.cc