Use a single ToplevelWindowEventHandler for the ash::Shell

ash/metrics/user_metrics_recorder.cc

Index: ash/metrics/user_metrics_recorder.cc
diff --git a/ash/metrics/user_metrics_recorder.cc b/ash/metrics/user_metrics_recorder.cc
index fdf1663e064772424575e2f119a95663b648d223..ee7e657d4b86c3e102dd16a202ae7ed087527006 100644
--- a/ash/metrics/user_metrics_recorder.cc
+++ b/ash/metrics/user_metrics_recorder.cc
@@ -79,6 +79,14 @@ void UserMetricsRecorder::RecordUserMetricsAction(UserMetricsAction action) {
     case ash::UMA_MOUSE_DOWN:
       content::RecordAction(content::UserMetricsAction("Mouse_Down"));
       break;
+    case ash::UMA_PANEL_MINIMIZE_CAPTION_CLICK:
+      content::RecordAction(
+          content::UserMetricsAction("Panel_Minimize_Caption_Click"));
+      break;
+    case ash::UMA_PANEL_MINIMIZE_CAPTION_GESTURE:
+      content::RecordAction(
+          content::UserMetricsAction("Panel_Minimize_Caption_Gesture"));
+      break;
     case ash::UMA_SHELF_ALIGNMENT_SET_BOTTOM:
       content::RecordAction(
           content::UserMetricsAction("Shelf_AlignmentSetBottom"));