Fix issue with longpress drag selection motion

ui/touch_selection/longpress_drag_selector_unittest.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/touch_selection/longpress_drag_selector.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/events/test/motion_event_test_utils.h"
 
 using ui::test::MockMotionEvent;
@@ skipping 121 matching lines @@
   // Activate a longpress-triggered selection.
   gfx::PointF selection_start(0, 10);
   gfx::PointF selection_end(10, 10);
   selector.OnLongPressEvent(event.GetEventTime(), gfx::PointF());
   EXPECT_TRUE(GetAndResetActiveStateChanged());
   SetSelection(selection_start, selection_end);
   selector.OnSelectionActivated();
   EXPECT_FALSE(IsDragging());
 
   // Initiate drag motion.
-  EXPECT_TRUE(selector.WillHandleTouchEvent(event.MovePoint(0, 0, 0)));
+  EXPECT_TRUE(selector.WillHandleTouchEvent(event.MovePoint(0, 5, 0)));
   EXPECT_FALSE(IsDragging());
 
   // As the initial motion is leftward, toward the selection start, the
   // selection start should be the drag point.
   EXPECT_TRUE(selector.WillHandleTouchEvent(event.MovePoint(0, -kSlop, 0)));
   EXPECT_TRUE(IsDragging());
   EXPECT_EQ(selection_start, DragPosition());
 
   EXPECT_TRUE(selector.WillHandleTouchEvent(event.MovePoint(0, 0, -kSlop)));
   EXPECT_TRUE(IsDragging());
@@ skipping 170 matching lines @@
   EXPECT_FALSE(IsDragging());
 
   // Subsequent motion should not be consumed.
   EXPECT_FALSE(selector.WillHandleTouchEvent(event.MovePoint(0, 0, 0)));
   EXPECT_FALSE(selector.WillHandleTouchEvent(event.MovePoint(0, 0, kSlop)));
   EXPECT_FALSE(selector.WillHandleTouchEvent(event.MovePoint(0, 0, kSlop * 2)));
   EXPECT_FALSE(IsDragging());
   EXPECT_FALSE(selector.WillHandleTouchEvent(event.ReleasePoint()));
 }
 
+TEST_F(LongPressDragSelectorTest, DragFast) {
+  LongPressDragSelector selector(this);
+  MockMotionEvent event;
+
+  // Start a touch sequence.
+  EXPECT_FALSE(selector.WillHandleTouchEvent(event.PressPoint(0, 0)));
+  EXPECT_FALSE(GetAndResetActiveStateChanged());
+
+  // Activate a longpress-triggered selection.
+  gfx::PointF selection_start(0, 10);
+  gfx::PointF selection_end(10, 10);
+  selector.OnLongPressEvent(event.GetEventTime(), gfx::PointF());
+  EXPECT_TRUE(GetAndResetActiveStateChanged());
+  SetSelection(selection_start, selection_end);
+  selector.OnSelectionActivated();
+  EXPECT_FALSE(IsDragging());
+
+  // Initiate drag motion.
+  EXPECT_TRUE(selector.WillHandleTouchEvent(event.MovePoint(0, 15, 5)));
+  EXPECT_FALSE(IsDragging());
+
+  // As the initial motion exceeds both endpoints, the closer bound should
+  // be used for dragging, in this case the selection end.
+  EXPECT_TRUE(selector.WillHandleTouchEvent(
+      event.MovePoint(0, 15.f + kSlop * 2.f, 5.f + kSlop)));
+  EXPECT_TRUE(IsDragging());
+  EXPECT_EQ(selection_end, DragPosition());
+
+  // Release the touch sequence, ending the drag.
+  EXPECT_FALSE(selector.WillHandleTouchEvent(event.ReleasePoint()));
+  EXPECT_FALSE(IsDragging());
+  EXPECT_TRUE(GetAndResetActiveStateChanged());
+}
+
 }  // namespace ui