Remove the touch ack timeout handler out of the legacy touch event queue.

content/browser/renderer_host/input/touch_timeout_handler.cc

Index: content/browser/renderer_host/input/touch_timeout_handler.cc
diff --git a/content/browser/renderer_host/input/touch_timeout_handler.cc b/content/browser/renderer_host/input/touch_timeout_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a3bf25642ff92c79a402a7534b9465ff22e58f09
--- /dev/null
+++ b/content/browser/renderer_host/input/touch_timeout_handler.cc
@@ -0,0 +1,216 @@
+// Copyright 2017 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_timeout_handler.h"
+
+#include <utility>
+
+#include "base/auto_reset.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/trace_event/trace_event.h"
+#include "content/browser/renderer_host/input/touch_event_queue.h"
+#include "content/common/input/web_touch_event_traits.h"
+#include "ui/events/base_event_utils.h"
+#include "ui/gfx/geometry/point_f.h"
+
+using blink::WebInputEvent;
+using blink::WebTouchEvent;
+using blink::WebTouchPoint;
+using ui::LatencyInfo;
+
+namespace content {
+namespace {
+
+bool ShouldTouchTriggerTimeout(const WebTouchEvent& event) {
+  return (event.type() == WebInputEvent::TouchStart ||
+          event.type() == WebInputEvent::TouchMove) &&
+         event.dispatchType == WebInputEvent::Blocking;
+}
+
+}  // namespace
+
+TouchTimeoutHandler::TouchTimeoutHandler(TouchEventQueue* touch_queue,
+                                         base::TimeDelta desktop_timeout_delay,
+                                         base::TimeDelta mobile_timeout_delay)
+    : touch_queue_(touch_queue),
+      desktop_timeout_delay_(desktop_timeout_delay),
+      mobile_timeout_delay_(mobile_timeout_delay),
+      use_mobile_timeout_(false),
+      pending_ack_state_(PENDING_ACK_NONE),
+      timeout_monitor_(
+          base::Bind(&TouchTimeoutHandler::OnTimeOut, base::Unretained(this))),
+      enabled_(true),
+      enabled_for_current_sequence_(false),
+      sequence_awaiting_uma_update_(false),
+      sequence_using_mobile_timeout_(false) {
+  SetUseMobileTimeout(false);
+}
+
+TouchTimeoutHandler::~TouchTimeoutHandler() {
+  LogSequenceEndForUMAIfNecessary(false);
+}
+
+void TouchTimeoutHandler::StartIfNecessary(
+    const TouchEventWithLatencyInfo& event) {
+  if (pending_ack_state_ != PENDING_ACK_NONE)
+    return;
+
+  if (!enabled_)
+    return;
+
+  const base::TimeDelta timeout_delay = GetTimeoutDelay();
+  if (timeout_delay.is_zero())
+    return;
+
+  if (!ShouldTouchTriggerTimeout(event.event))
+    return;
+
+  if (WebTouchEventTraits::IsTouchSequenceStart(event.event)) {
+    LogSequenceStartForUMA();
+    enabled_for_current_sequence_ = true;
+  }
+
+  if (!enabled_for_current_sequence_)
+    return;
+
+  timeout_event_ = event;
+  timeout_monitor_.Restart(timeout_delay);
+}
+
+bool TouchTimeoutHandler::ConfirmTouchEvent(uint32_t unique_touch_event_id,
+                                            InputEventAckState ack_result) {
+  if (timeout_event_.event.uniqueTouchEventId != unique_touch_event_id)
+    return false;
+
+  switch (pending_ack_state_) {
+    case PENDING_ACK_NONE:
+      if (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED)
+        enabled_for_current_sequence_ = false;
+      timeout_monitor_.Stop();
+      return false;
+    case PENDING_ACK_ORIGINAL_EVENT:
+      if (AckedTimeoutEventRequiresCancel(ack_result)) {
+        SetPendingAckState(PENDING_ACK_CANCEL_EVENT);
+        touch_queue_->SendTouchCancelEventForTouchEvent(timeout_event_);
+      } else {
+        SetPendingAckState(PENDING_ACK_NONE);
+        touch_queue_->UpdateTouchConsumerStates(timeout_event_.event,
+                                                ack_result);
+      }
+      return true;
+    case PENDING_ACK_CANCEL_EVENT:
+      SetPendingAckState(PENDING_ACK_NONE);
+      return true;
+  }
+  return false;
+}
+
+bool TouchTimeoutHandler::FilterEvent(const WebTouchEvent& event) {
+  if (!HasTimeoutEvent())
+    return false;
+
+  if (WebTouchEventTraits::IsTouchSequenceStart(event)) {
+    // If a new sequence is observed while we're still waiting on the
+    // timed-out sequence response, also count the new sequence as timed-out.
+    LogSequenceStartForUMA();
+    LogSequenceEndForUMAIfNecessary(true);
+  }
+
+  return true;
+}
+
+void TouchTimeoutHandler::SetEnabled(bool enabled) {
+  if (enabled_ == enabled)
+    return;
+
+  enabled_ = enabled;
+
+  if (enabled_)
+    return;
+
+  enabled_for_current_sequence_ = false;
+  // Only reset the |timeout_handler_| if the timer is running and has not
+  // yet timed out. This ensures that an already timed out sequence is
+  // properly flushed by the handler.
+  if (IsTimeoutTimerRunning()) {
+    pending_ack_state_ = PENDING_ACK_NONE;
+    timeout_monitor_.Stop();
+  }
+}
+
+void TouchTimeoutHandler::SetUseMobileTimeout(bool use_mobile_timeout) {
+  use_mobile_timeout_ = use_mobile_timeout;
+}
+
+void TouchTimeoutHandler::OnTimeOut() {
+  LogSequenceEndForUMAIfNecessary(true);
+  SetPendingAckState(PENDING_ACK_ORIGINAL_EVENT);
+  touch_queue_->FlushQueue();
+}
+
+// Skip a cancel event if the timed-out event had no consumer and was the
+// initial event in the gesture.
+bool TouchTimeoutHandler::AckedTimeoutEventRequiresCancel(
+    InputEventAckState ack_result) const {
+  DCHECK(HasTimeoutEvent());
+  if (ack_result != INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS)
+    return true;
+  return !WebTouchEventTraits::IsTouchSequenceStart(timeout_event_.event);
+}
+
+void TouchTimeoutHandler::SetPendingAckState(
+    PendingAckState new_pending_ack_state) {
+  DCHECK_NE(pending_ack_state_, new_pending_ack_state);
+  switch (new_pending_ack_state) {
+    case PENDING_ACK_ORIGINAL_EVENT:
+      DCHECK_EQ(pending_ack_state_, PENDING_ACK_NONE);
+      TRACE_EVENT_ASYNC_BEGIN0("input", "TouchEventTimeout", this);
+      break;
+    case PENDING_ACK_CANCEL_EVENT:
+      DCHECK_EQ(pending_ack_state_, PENDING_ACK_ORIGINAL_EVENT);
+      DCHECK(!timeout_monitor_.IsRunning());
+      DCHECK(touch_queue_->Empty());
+      TRACE_EVENT_ASYNC_STEP_INTO0("input", "TouchEventTimeout", this,
+                                   "CancelEvent");
+      break;
+    case PENDING_ACK_NONE:
+      DCHECK(!timeout_monitor_.IsRunning());
+      DCHECK(touch_queue_->Empty());
+      TRACE_EVENT_ASYNC_END0("input", "TouchEventTimeout", this);
+      break;
+  }
+  pending_ack_state_ = new_pending_ack_state;
+}
+
+void TouchTimeoutHandler::LogSequenceStartForUMA() {
+  // Always flush any unlogged entries before starting a new one.
+  LogSequenceEndForUMAIfNecessary(false);
+  sequence_awaiting_uma_update_ = true;
+  sequence_using_mobile_timeout_ = use_mobile_timeout_;
+}
+
+void TouchTimeoutHandler::LogSequenceEndForUMAIfNecessary(bool timed_out) {
+  if (!sequence_awaiting_uma_update_)
+    return;
+
+  sequence_awaiting_uma_update_ = false;
+
+  if (sequence_using_mobile_timeout_) {
+    UMA_HISTOGRAM_BOOLEAN("Event.Touch.TimedOutOnMobileSite", timed_out);
+  } else {
+    UMA_HISTOGRAM_BOOLEAN("Event.Touch.TimedOutOnDesktopSite", timed_out);
+  }
+}
+
+base::TimeDelta TouchTimeoutHandler::GetTimeoutDelay() const {
+  return use_mobile_timeout_ ? mobile_timeout_delay_ : desktop_timeout_delay_;
+}
+
+bool TouchTimeoutHandler::HasTimeoutEvent() const {
+  return pending_ack_state_ != PENDING_ACK_NONE;
+}
+
+}  // namespace content