Use stricter type checking in UMA_HISTOGRAM_ENUMERATION

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 e9d4938b410d114642ee6861582f3467486ce610..bcffd3e51d1140d10f48f3d945ae5754c0e22bae 100644
--- a/ash/shelf/shelf_view.cc
+++ b/ash/shelf/shelf_view.cc
@@ -677,10 +677,11 @@ void ShelfView::PointerPressedOnButton(views::View* view,
   drag_view_ = static_cast<ShelfButton*>(view);
   drag_origin_ = gfx::Point(event.x(), event.y());
   UMA_HISTOGRAM_ENUMERATION("Ash.ShelfAlignmentUsage",
-                            shelf_->SelectValueForShelfAlignment(
-                                SHELF_ALIGNMENT_UMA_ENUM_VALUE_BOTTOM,
-                                SHELF_ALIGNMENT_UMA_ENUM_VALUE_LEFT,
-                                SHELF_ALIGNMENT_UMA_ENUM_VALUE_RIGHT),
+                            static_cast<ShelfAlignmentUmaEnumValue>(
+                                shelf_->SelectValueForShelfAlignment(
+                                    SHELF_ALIGNMENT_UMA_ENUM_VALUE_BOTTOM,
+                                    SHELF_ALIGNMENT_UMA_ENUM_VALUE_LEFT,
+                                    SHELF_ALIGNMENT_UMA_ENUM_VALUE_RIGHT)),
                             SHELF_ALIGNMENT_UMA_ENUM_VALUE_COUNT);
 }