UMA stats for stylus usage

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index 941bdbc94689b47889aeb6ddaaf3bf13f0c68226..94872249d001172e8af3db1155176f500122c7ee 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -36,6 +36,10 @@
 #include "ui/wm/core/shadow_types.h"
 #include "ui/wm/core/window_util.h"
 
+#if defined(OS_CHROMEOS)
+#include "ash/shared/app_types.h"
+#endif
+
 DECLARE_WINDOW_PROPERTY_TYPE(std::string*)
 
 namespace exo {
@@ -940,6 +944,11 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
   SetApplicationId(window, &application_id_);
   SetMainSurface(window, surface_);
 
+#if defined(OS_CHROMEOS)
+  window->SetProperty(aura::client::kAppType,
+                      static_cast<int>(ash::AppType::ARC_APP));

[reveman, 2016/09/27 20:39:00]

This is incorrect. All shell surfaces are not arc apps. You can use the
kApplicationIdKey window property to detect if a window is from an arc app. It's
set to org.chromium.arc.* for arc apps. However, this type of detection doesn't
belong in exo code. Arc specific code should handle this. Maybe we can add it to
components/arc or the arc launcher code.

[xiaoyinh(OOO Sep 11-29), 2016/09/29 20:37:44]

Thanks for pointing it out. I have moved it to
arc_app_window_launcher_controller.cc

+#endif
+
   // Start tracking changes to window bounds and window state.
   window->AddObserver(this);
   ash::wm::WindowState* window_state = ash::wm::GetWindowState(window);