Stick windows to sides of workspaces

ash/shell_window_ids.h

Index: ash/shell_window_ids.h
diff --git a/ash/shell_window_ids.h b/ash/shell_window_ids.h
index a64858fccb52377f021e4922a451f062f3d88c49..f4b9d1ced48410151858aba3bbd6752ebc441971 100644
--- a/ash/shell_window_ids.h
+++ b/ash/shell_window_ids.h
@@ -99,6 +99,9 @@ const int kShellWindowId_PhantomWindow = 21;
 // The topmost container, used for power off animation.
 const int kShellWindowId_PowerButtonAnimationContainer = 22;
 
+// The container for windows docked to the sides.
+const int kShellWindowId_DockContainer = 23;
+
 }  // namespace internal
 
 }  // namespace ash