Windows docking should get triggered by pressing against the screen edge

ash/wm/workspace/workspace_window_resizer.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_WINDOW_RESIZER_H_
 #define ASH_WM_WORKSPACE_WINDOW_RESIZER_H_
 
 #include <vector>
 
 #include "ash/wm/window_resizer.h"
 #include "ash/wm/workspace/magnetism_matcher.h"
+#include "ash/wm/workspace/snap_types.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "ui/aura/window_tracker.h"
 
 namespace ash {
 namespace internal {
 
 class PhantomWindowController;
 class SnapSizer;
 class WindowSize;
 
 // WindowResizer implementation for workspaces. This enforces that windows are
@@ skipping 39 matching lines @@
 
  private:
   WorkspaceWindowResizer(const Details& details,
                          const std::vector<aura::Window*>& attached_windows);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(WorkspaceWindowResizerTest, CancelSnapPhantom);
   FRIEND_TEST_ALL_PREFIXES(WorkspaceWindowResizerTest, PhantomSnapMaxSize);
   FRIEND_TEST_ALL_PREFIXES(WorkspaceWindowResizerTest, PhantomWindowShow);
 
-  // Type of snapping.
-  enum SnapType {
-    // Snap to the left/right edge of the screen.
-    SNAP_LEFT_EDGE,
-    SNAP_RIGHT_EDGE,
-
-    // No snap position.
-    SNAP_NONE
-  };
-
   // Returns the final bounds to place the window at. This differs from
   // the current when snapping.
   gfx::Rect GetFinalBounds(const gfx::Rect& bounds) const;
 
   // Lays out the attached windows. |bounds| is the bounds of the main window.
   void LayoutAttachedWindows(gfx::Rect* bounds);
 
   // Calculates the new sizes of the attached windows, given that the main
   // window has been resized (along the primary axis) by |delta|.
   // |available_size| is the maximum length of the space that the attached
@@ skipping 110 matching lines @@
   // Window the drag has magnetically attached to.
   aura::Window* magnetism_window_;
 
   // Used to verify |magnetism_window_| is still valid.
   aura::WindowTracker window_tracker_;
 
   // If |magnetism_window_| is non-NULL this indicates how the two windows
   // should attach.
   MatchedEdge magnetism_edge_;
 
+  // Used to determine if this has been deleted during a drag such as when a tab
+  // gets dragged into another browser window.
+  base::WeakPtrFactory<WorkspaceWindowResizer> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(WorkspaceWindowResizer);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_WINDOW_RESIZER_H_