Stick windows to sides of workspaces

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 424e47d29f4890086fa5d3e49d694360e1a3eb2b..dcdff7172bd2e7e8c17f7e7cdfb884b0256d0f3a 100644
--- a/ash/wm/workspace/workspace_window_resizer.h
+++ b/ash/wm/workspace/workspace_window_resizer.h
@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "ash/wm/property_util.h"
 #include "ash/wm/window_resizer.h"
 #include "ash/wm/workspace/magnetism_matcher.h"
 #include "base/compiler_specific.h"
@@ -190,6 +191,11 @@ class ASH_EXPORT WorkspaceWindowResizer : public WindowResizer {
   // Last SnapType.
   SnapType snap_type_;
 
+  // Last updated touched edge. We track it until |this| instance gets destroyed
+  // at which point a property gets updated and observers get called to add the
+  // window to the dock if necessary.
+  ash::DockEdge dock_edge_;
+
   // Number of mouse moves since the last bounds change. Only used for phantom
   // placement to track when the mouse is moved while pushed against the edge of
   // the screen.