Update shelf spacing in Chrome OS according to the MD specs

ash/root_window_controller_unittest.cc

Index: ash/root_window_controller_unittest.cc
diff --git a/ash/root_window_controller_unittest.cc b/ash/root_window_controller_unittest.cc
index 58ccc2e0fc3392ac5436ee3b369fdbfd92b32074..5487123bf27d7e85394050ef087da0e0210e4157 100644
--- a/ash/root_window_controller_unittest.cc
+++ b/ash/root_window_controller_unittest.cc
@@ -8,6 +8,7 @@
 
 #include "ash/display/display_manager.h"
 #include "ash/session/session_state_delegate.h"
+#include "ash/shelf/shelf_constants.h"

[bruthig, 2016/05/25 20:24:52]

Is this needed?  This file doesn't appear to actually reference anything from
shelf_constants.h other than the comment.

[yiyix, 2016/06/02 03:54:53]

Done.

 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ -205,7 +206,7 @@ TEST_F(RootWindowControllerTest, MoveWindows_Basic) {
             normal->GetNativeView()->GetBoundsInRootWindow().ToString());
 
   // Maximized area on primary display has 3px (given as
-  // kAutoHideSize in shelf_layout_manager.cc) inset at the bottom.
+  // kAutoHideSize in shelf_constants.cc) inset at the bottom.
 
   // First clear fullscreen status, since both fullscreen and maximized windows
   // share the same desktop workspace, which cancels the shelf status.