Added Launcher_MinimizeTask UMA user action.

ash/shelf/shelf_view.cc

Index: ash/shelf/shelf_view.cc
diff --git a/ash/shelf/shelf_view.cc b/ash/shelf/shelf_view.cc
index 06d6dd41ef1ba99601b3436417df550b8acaa3c5..f46233c74f0a3d2c5ff0e13779108f2fb591e263 100644
--- a/ash/shelf/shelf_view.cc
+++ b/ash/shelf/shelf_view.cc
@@ -1768,7 +1768,6 @@ void ShelfView::RecordIconActivatedAction(
     ShelfItemDelegate::PerformedAction performed_action) {
   switch (performed_action) {
     case ShelfItemDelegate::kNoAction:
-    case ShelfItemDelegate::kExistingWindowMinimized:
     case ShelfItemDelegate::kAppListMenuShown:
       break;
     case ShelfItemDelegate::kNewWindowCreated:
@@ -1779,6 +1778,10 @@ void ShelfView::RecordIconActivatedAction(
       Shell::GetInstance()->metrics()->RecordUserMetricsAction(
           UMA_LAUNCHER_SWITCH_TASK);
       break;
+    case ShelfItemDelegate::kExistingWindowMinimized:
+      Shell::GetInstance()->metrics()->RecordUserMetricsAction(
+          UMA_LAUNCHER_MINIMIZE_TASK);
+      break;
   }
 }