Stop sending an async touchmove for the app slop region

content/browser/renderer_host/input/touch_event_queue_unittest.cc

 // Copyright 2013 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 "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "content/browser/renderer_host/input/timeout_monitor.h"
 #include "content/browser/renderer_host/input/touch_event_queue.h"
@@ skipping 1918 matching lines @@
   EXPECT_EQ(1U, queued_event_count());
   EXPECT_EQ(1U, GetAndResetSentEventCount());
   EXPECT_EQ(1U, GetAndResetAckedEventCount());
 
   SendTouchEventAck(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
   EXPECT_EQ(0U, queued_event_count());
   EXPECT_EQ(0U, GetAndResetSentEventCount());
   EXPECT_EQ(1U, GetAndResetAckedEventCount());
 }
 
+TEST_F(TouchEventQueueTest, AsyncTouchDeferredDuringTouchAck) {
+  SetTouchScrollingMode(TouchEventQueue::TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE);
+
+  // Initiate scroll-induced touch throttling.
+  PressTouchPoint(0, 0);
+  SendTouchEventAck(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
+  EXPECT_EQ(1U, GetAndResetSentEventCount());
+  EXPECT_EQ(1U, GetAndResetAckedEventCount());
+
+  MoveTouchPoint(0, 0, 5);
+  EXPECT_EQ(1U, queued_event_count());
+  EXPECT_EQ(1U, GetAndResetSentEventCount());
+  EXPECT_EQ(0U, GetAndResetAckedEventCount());
+  SendGestureEvent(WebInputEvent::GestureScrollBegin);
+  SendGestureEvent(WebInputEvent::GestureScrollUpdate);
+
+  // Now queue a touchmove that exceeds the application slop region.
+  MoveTouchPoint(0, 0, 20);
+  EXPECT_FALSE(HasPendingAsyncTouchMove());
+  EXPECT_EQ(2U, queued_event_count());
+  EXPECT_EQ(0U, GetAndResetSentEventCount());
+  EXPECT_EQ(0U, GetAndResetAckedEventCount());
+
+  // Despite the second touchmove exceeding the application slop region, its
+  // sending will be deferred until after the original touch was ack'ed.
+  SendTouchEventAck(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
+  EXPECT_TRUE(HasPendingAsyncTouchMove());
+  EXPECT_EQ(0U, queued_event_count());
+  EXPECT_EQ(0U, GetAndResetSentEventCount());
+  EXPECT_EQ(2U, GetAndResetAckedEventCount());
+
+  // A subsequent touchmove will flush the deferred async touchmove,

[Rick Byers, 2015/01/27 17:59:15]

coalescing means it's more like 'replace' than 'flush', right?  Perhaps it's
worth having the test check the co-ordinate of the event here, verifying
coalescing occurred?

+  MoveTouchPoint(0, 0, 25);
+  EXPECT_FALSE(HasPendingAsyncTouchMove());
+  EXPECT_FALSE(sent_event().cancelable);
+  EXPECT_EQ(1U, GetAndResetSentEventCount());
+  EXPECT_EQ(0U, GetAndResetAckedEventCount());
+}
+
 // Ensure that async touch dispatch and touch ack timeout interactions work
 // appropriately.
 TEST_F(TouchEventQueueTest, AsyncTouchWithAckTimeout) {
   SetTouchScrollingMode(TouchEventQueue::TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE);
   SetUpForTimeoutTesting(DefaultTouchTimeoutDelay());
 
   // The touchstart should start the timeout.
   PressTouchPoint(0, 0);
   EXPECT_EQ(1U, GetAndResetSentEventCount());
   EXPECT_TRUE(IsTimeoutRunning());
@@ skipping 300 matching lines @@
 
   // Give the touchmove a valid id; it should be sent.
   event.touches[0].id = press_id;
   SendTouchEvent(event);
   EXPECT_EQ(1U, GetAndResetSentEventCount());
   SendTouchEventAck(INPUT_EVENT_ACK_STATE_CONSUMED);
   EXPECT_EQ(1U, GetAndResetAckedEventCount());
 }
 
 }  // namespace content