Windows docking should get triggered by pressing against the screen edge

ash/wm/workspace/snap_sizer.h

 // Copyright (c) 2012 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.
 
 #ifndef ASH_WM_WORKSPACE_SNAP_SIZER_H_
 #define ASH_WM_WORKSPACE_SNAP_SIZER_H_
 
 #include <vector>
 
 #include "ash/ash_export.h"
@@ skipping 45 matching lines @@
   // then it returns the next snap-bounds).
   gfx::Rect GetSnapBounds(const gfx::Rect& bounds);
 
   // Set the snap sizer to the button press default size and prevent resizing.
   void SelectDefaultSizeAndDisableResize();
 
   // Returns the target bounds based on the edge and the provided |size_index|.
   // For unit test purposes this function is not private.
   gfx::Rect GetTargetBoundsForSize(size_t size_index) const;
 
+  // Returns true when snapping sequence is at its last (docking) step.
+  bool end_of_sequence() const { return end_of_sequence_; }
+
  private:
   // Calculates the amount to increment by. This returns one of -1, 0 or 1 and
   // is intended to by applied to |size_index_|. |x| is the current
   // x-coordinate, and |reference_x| is used to determine whether to increase
   // or decrease the position. It's one of |last_adjust_x_| or |last_update_x_|.
   int CalculateIncrement(int x, int reference_x) const;
 
   // Changes the bounds. |x| is the current x-coordinate and |delta| the amount
   // to increase by. |delta| comes from CalculateIncrement() and is applied
   // to |size_index_|.
@@ skipping 13 matching lines @@
   // Current target bounds for the snap.
   gfx::Rect target_bounds_;
 
   // Time Update() was last invoked.
   base::TimeTicks time_last_update_;
 
   // Index into |kSizes| that dictates the width of the screen the target
   // bounds should get.
   int size_index_;
 
+  // Set to true when an attempt is made to increment |size_index_| past
+  // the size of |usable_width_|.
+  bool end_of_sequence_;
+
   // If set, |size_index_| will get ignored and the single button default
   // setting will be used instead.
   bool resize_disabled_;
 
   // Number of times Update() has been invoked since last ChangeBounds().
   int num_moves_since_adjust_;
 
   // X-coordinate the last time ChangeBounds() was invoked.
   int last_adjust_x_;
 
@@ skipping 12 matching lines @@
   // sizer gets created.
   const std::vector<int> usable_width_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapSizer);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_SNAP_SIZER_H_