Touch emulator: allow multiple touch streams.

content/browser/renderer_host/input/touch_stream_tracker.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/renderer_host/input/touch_stream_tracker.h"
+
+#include "content/common/input/web_touch_event_traits.h"
+
+namespace content {
+
+TouchStreamTracker::TouchStreamTracker()
+    : has_active_touch_stream_(false) {
+}
+
+TouchStreamTracker::~TouchStreamTracker() {
+}
+
+InputEventAckState TouchStreamTracker::FilterTouchEventFromStream(
+    const blink::WebTouchEvent& touch_event, TouchStream stream) {
+  if (has_active_touch_stream_ && active_touch_stream_ != stream)
+    return INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS;

[jdduke (slow), 2014/07/10 14:52:58]

We probably want to return INPUT_EVENT_ACK_STATE_CONSUMED, as otherwise the UI
will do things with the touch that we may not want (e.g., gesture detection).

+  has_active_touch_stream_ = true;
+  active_touch_stream_ = stream;
+  return INPUT_EVENT_ACK_STATE_UNKNOWN;
+}
+
+TouchStreamTracker::TouchStream TouchStreamTracker::OnTouchEventAck(
+    const TouchEventWithLatencyInfo& event, InputEventAckState ack_result) {
+  DCHECK(has_active_touch_stream_);
+  if (WebTouchEventTraits::IsTouchSequenceEnd(event.event))
+    has_active_touch_stream_ = false;
+  return active_touch_stream_;
+}
+
+}  // namespace content