Improved eventSender handling of non-consecutive touch ids.
Improved eventSender handling of non-consecutive touch ids.

After event_sender sees a sequence of touch-cancels or
touch-releases that makes the current touch ids
non-consecutive, it can create duplicate touch-ids for newly
added touch points. See the bug for details. This CL fixes
this problem.

Moreover, event_sender cleans its cache of released touches
but not the canceled ones in SendCurrentTouchEvent. This CL
takes care of this too.

BUG=529807

Review URL: https://codereview.chromium.org/1317733006

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#347990}

CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend