Windows docking should get triggered by pressing against the screen edge

ash/wm/workspace/workspace_window_resizer.h

Index: ash/wm/workspace/workspace_window_resizer.h
diff --git a/ash/wm/workspace/workspace_window_resizer.h b/ash/wm/workspace/workspace_window_resizer.h
index 76176b1a2b4a77fa7b1ad3b4a75eafded2a7e282..1759e4e81443ad2c5d3932e03c6288bb47827483 100644
--- a/ash/wm/workspace/workspace_window_resizer.h
+++ b/ash/wm/workspace/workspace_window_resizer.h
@@ -9,9 +9,11 @@
 
 #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 {
@@ -71,16 +73,6 @@ class ASH_EXPORT WorkspaceWindowResizer : public WindowResizer {
   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;
@@ -211,6 +203,10 @@ class ASH_EXPORT WorkspaceWindowResizer : public WindowResizer {
   // 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);
 };