Add AppWindow.setVisibleOnAllWorkspaces.

apps/app_window.cc

Index: apps/app_window.cc
diff --git a/apps/app_window.cc b/apps/app_window.cc
index 3f7aa84a6704f155f5b102a3f2d0d30e1cb29dc4..adac9d9ef795d98619965585c3774e9969388183 100644
--- a/apps/app_window.cc
+++ b/apps/app_window.cc
@@ -166,7 +166,8 @@ AppWindow::CreateParams::CreateParams()
       hidden(false),
       resizable(true),
       focused(true),
-      always_on_top(false) {
+      always_on_top(false),
+      visible_on_all_workspaces(false) {
 }
 
 AppWindow::CreateParams::~CreateParams() {}
@@ -735,6 +736,11 @@ void AppWindow::GetSerializedState(base::DictionaryValue* properties) const {
   properties->SetBoolean(
       "alphaEnabled",
       requested_alpha_enabled_ && native_app_window_->CanHaveAlphaEnabled());
+#if defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+  properties->SetBoolean("canSetVisibleOnAllWorkspaces", true);
+#else
+  properties->SetBoolean("canSetVisibleOnAllWorkspaces", false);
+#endif
 
   // These properties are undocumented and are to enable testing. Alpha is
   // removed to