The helper functions for slop region check and subtraction are modified.

ui/events/test/motion_event_test_utils.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 "ui/events/test/motion_event_test_utils.h"
 
 #include <sstream>
 
 #include "base/logging.h"
 #include "ui/events/base_event_utils.h"
@@ skipping 101 matching lines @@
   float dy = x - p.y;
   p.x = x;
   p.y = y;
   p.raw_x += dx;
   p.raw_y += dy;
   set_action(ACTION_MOVE);
   return *this;
 }
 
 MockMotionEvent& MockMotionEvent::ReleasePoint() {
+  DCHECK_GT(GetPointerCount(), 0U);
+  switch (GetAction()) {
+    // If the previous action is one of those who need removing a pointer in
+    // UpdatePointersAndID, then the last index will be GetPointerCount() - 2.
+    case ACTION_POINTER_UP:
+    case ACTION_UP:
+    case ACTION_CANCEL:
+      return ReleasePointAtIndex(GetPointerCount() - 2);
+      break;
+    default:
+      break;
+  }
+  return ReleasePointAtIndex(GetPointerCount() - 1);
+}
+
+MockMotionEvent& MockMotionEvent::ReleasePointAtIndex(size_t index) {
   UpdatePointersAndID();
-  DCHECK_GT(GetPointerCount(), 0U);
+  DCHECK_LT(index, GetPointerCount());
   if (GetPointerCount() > 1) {
-    set_action_index(static_cast<int>(GetPointerCount()) - 1);
+    set_action_index(static_cast<int>(index));
     set_action(ACTION_POINTER_UP);
   } else {
     set_action(ACTION_UP);
   }
   return *this;
 }
 
 MockMotionEvent& MockMotionEvent::CancelPoint() {
   UpdatePointersAndID();
   DCHECK_GT(GetPointerCount(), 0U);
@@ skipping 22 matching lines @@
   pointer(pointer_index).tool_type = tool_type;
   return *this;
 }
 
 void MockMotionEvent::PushPointer(float x, float y) {
   MotionEventGeneric::PushPointer(
       CreatePointer(x, y, static_cast<int>(GetPointerCount())));
 }
 
 void MockMotionEvent::UpdatePointersAndID() {
-  set_action_index(-1);
   set_unique_event_id(ui::GetNextTouchEventId());
   switch (GetAction()) {
+    case ACTION_POINTER_UP: {
+      int index = GetActionIndex();
+      DCHECK_LT(index, static_cast<int>(GetPointerCount()));
+      RemovePointerAt(index);
+      break;
+    }
     case ACTION_UP:
-    case ACTION_POINTER_UP:
     case ACTION_CANCEL:
       PopPointer();
-      return;
+      break;
     default:
       break;
   }
+  set_action_index(-1);
 }
 
 MockMotionEvent& MockMotionEvent::SetPrimaryPointerId(int id) {
   DCHECK_GT(GetPointerCount(), 0U);
   pointer(0).id = id;
   return *this;
 }
 
 std::string ToString(const MotionEvent& event) {
   std::stringstream ss;
@@ skipping 43 matching lines @@
         ss << ", ";
     }
     ss << "]\n}";
   }
 
   return ss.str();
 }
 
 }  // namespace test
 }  // namespace ui