Cros Tablet: Add UMA stats for the user close actions in tablet mode.

ash/wm/overview/window_selector_item.cc

Index: ash/wm/overview/window_selector_item.cc
diff --git a/ash/wm/overview/window_selector_item.cc b/ash/wm/overview/window_selector_item.cc
index 0cf23ccd1da399f56cd8452c3f8d2d16bc9c96ef..723e54bbaeb3811fa62c5cb4153177db84fc7efc 100644
--- a/ash/wm/overview/window_selector_item.cc
+++ b/ash/wm/overview/window_selector_item.cc
@@ -11,7 +11,9 @@
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/resources/vector_icons/vector_icons.h"
 #include "ash/root_window_controller.h"
+#include "ash/shell.h"
 #include "ash/shell_port.h"
+#include "ash/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/wm/overview/cleanup_animation_observer.h"
 #include "ash/wm/overview/overview_animation_type.h"
 #include "ash/wm/overview/scoped_overview_animation_settings.h"
@@ -530,6 +532,12 @@ void WindowSelectorItem::ButtonPressed(views::Button* sender,
                                        const ui::Event& event) {
   if (sender == close_button_) {
     ShellPort::Get()->RecordUserMetricsAction(UMA_WINDOW_OVERVIEW_CLOSE_BUTTON);
+    if (ash::Shell::Get()
+            ->maximize_mode_controller()
+            ->IsMaximizeModeWindowManagerEnabled()) {
+      ash::ShellPort::Get()->RecordUserMetricsAction(
+          ash::UMA_TABLET_WINDOW_CLOSE_THROUGH_OVERVIEW_CLOSE_BUTTON);
+    }
     CloseWindow();
     return;
   }