Allows tab dragging when maximized on aura. To fix it I made it so

ash/wm/workspace/workspace_layout_manager.h

Index: ash/wm/workspace/workspace_layout_manager.h
diff --git a/ash/wm/workspace/workspace_layout_manager.h b/ash/wm/workspace/workspace_layout_manager.h
index e350ad246454523c7ad351b6e546e11eb616b7a9..001a06c5380bbb73c91228500613dbf7f9e3fef5 100644
--- a/ash/wm/workspace/workspace_layout_manager.h
+++ b/ash/wm/workspace/workspace_layout_manager.h
@@ -10,6 +10,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/aura/layout_manager.h"
+#include "ui/aura/window_observer.h"
 
 namespace aura {
 class MouseEvent;
@@ -26,7 +27,8 @@ namespace internal {
 class WorkspaceManager;
 
 // LayoutManager for top level windows when WorkspaceManager is enabled.
-class ASH_EXPORT WorkspaceLayoutManager : public aura::LayoutManager {
+class ASH_EXPORT WorkspaceLayoutManager : public aura::LayoutManager,
+                                          public aura::WindowObserver {
  public:
   explicit WorkspaceLayoutManager(WorkspaceManager* workspace_manager);
   virtual ~WorkspaceLayoutManager();
@@ -45,6 +47,11 @@ class ASH_EXPORT WorkspaceLayoutManager : public aura::LayoutManager {
   virtual void SetChildBounds(aura::Window* child,
                               const gfx::Rect& requested_bounds) OVERRIDE;
 
+  // Overriden from aura::WindowObserver:
+  virtual void OnWindowPropertyChanged(aura::Window* window,
+                                       const void* key,
+                                       intptr_t old) OVERRIDE;
+
  private:
   // Owned by WorkspaceController.
   WorkspaceManager* workspace_manager_;