hide dragged window when attaching

The comment says about desktop-linux but the ifdef includes
ChromeOS unexpectedly. Seemingly this hiding actually resolves
gotchas happening on attaching, possibly because it can exclude
the window-to-disappear properly.

Bug: 930004
Test: manually
Change-Id: I2ee10e0cbdfc4b15c168e3c3c2c51b33d0a7b563
Reviewed-on: https://chromium-review.googlesource.com/c/1460859Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630564}

chrome/browser/ui/views/tabs/tab_drag_controller.cc

@@ -815,7 +815,7 @@ TabDragController::DragBrowserToNewTabStrip(TabStrip* target_tabstrip,
     else
       target_tabstrip->GetWidget()->SetCapture(attached_tabstrip_);
 
-#if !defined(OS_LINUX)
+#if !defined(OS_LINUX) || defined(OS_CHROMEOS)
     // EndMoveLoop is going to snap the window back to its original location.
     // Hide it so users don't see this. Hiding a window in Linux aura causes
     // it to lose capture so skip it.