Adjusts dragging logic to be less likely to trigger false positive switch from snapping to docking

ash/wm/workspace/two_step_edge_cycler.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 "ash/wm/workspace/two_step_edge_cycler.h"
 
 #include <cstdlib>
 
 namespace ash {
 namespace {
 
 // We cycle to the second mode if any of the following happens while the mouse
 // is on the edge of the workspace:
 // . The user stops moving the mouse for |kMaxDelay| and then moves the mouse
-//   again.
-// . The mouse moves |kMaxPixels| horizontal pixels.
-// . The mouse is moved |kMaxMoves| times.
-const int kMaxDelay = 500;
+//   again in the preferred direction from the last paused location for at least
+//   |kMaxPixelsAfterPause| horizontal pixels.
+// . The mouse moves |kMaxPixels| horizontal pixels in the preferred direction.
+// . The mouse is moved |kMaxMoves| times since the last pause.
+const int kMaxDelay = 400;
 const int kMaxPixels = 100;
+const int kMaxPixelsAfterPause = 10;
 const int kMaxMoves = 25;
 
 }  // namespace
 
-TwoStepEdgeCycler::TwoStepEdgeCycler(const gfx::Point& start)
+TwoStepEdgeCycler::TwoStepEdgeCycler(const gfx::Point& start,
+                                     TwoStepEdgeCycler::Direction direction)
     : second_mode_(false),
       time_last_move_(base::TimeTicks::Now()),
       num_moves_(0),
-      start_x_(start.x()) {
+      start_x_(start.x()),
+      paused_x_(start.x()),
+      paused_(false),
+      direction_(direction) {
 }
 
 TwoStepEdgeCycler::~TwoStepEdgeCycler() {
 }
 
 void TwoStepEdgeCycler::OnMove(const gfx::Point& location) {
   if (second_mode_)
     return;
 
+  if ((base::TimeTicks::Now() - time_last_move_).InMilliseconds() > kMaxDelay) {
+    paused_ = true;
+    paused_x_ = location.x();
+    num_moves_ = 0;
+  }
+  time_last_move_ = base::TimeTicks::Now();
+
+  int compare_x = paused_ ? paused_x_ : start_x_;
+  if (location.x() != compare_x &&
+      (location.x() < compare_x) != (direction_ == DIRECTION_LEFT)) {
+    return;
+  }
+
   ++num_moves_;
-  second_mode_ =
-      (base::TimeTicks::Now() - time_last_move_).InMilliseconds() >
-          kMaxDelay ||
-      std::abs(location.x() - start_x_) >= kMaxPixels ||
-      num_moves_ >= kMaxMoves;
-  time_last_move_ = base::TimeTicks::Now();
+  bool moved_in_the_same_direction_after_pause =
+      paused_ && std::abs(location.x() - paused_x_) >= kMaxPixelsAfterPause;
+  second_mode_ = moved_in_the_same_direction_after_pause ||
+                 std::abs(location.x() - start_x_) >= kMaxPixels ||
+                 num_moves_ >= kMaxMoves;
 }
 
 }  // namespace ash