Add a proper shadow to the experimental app list search box.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index e2d3e095d7634c6cfb9b4c98a322f152a5cf627c..cd773783d964157a154f05d0673b0932747ab627 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -109,6 +109,27 @@ class AppListOverlayView : public views::View {
   DISALLOW_COPY_AND_ASSIGN(AppListOverlayView);
 };
 
+// An event targeter for the search box widget which will ignore events that
+// are on the search box's shadow.
+class SearchBoxWindowTargeter : public wm::MaskedWindowTargeter {
+ public:
+  SearchBoxWindowTargeter(aura::Window* window, views::View* content_view)
+      : wm::MaskedWindowTargeter(window), content_view_(content_view) {}
+  ~SearchBoxWindowTargeter() override {}
+
+ private:
+  // wm::MaskedWindowTargeter:
+  bool GetHitTestMask(aura::Window* window, gfx::Path* mask) const override {
+    mask->addRect(gfx::RectToSkRect(content_view_->ConvertRectToWidget(
+        content_view_->GetContentsBounds())));
+    return true;
+  }
+
+  views::View* content_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(SearchBoxWindowTargeter);
+};
+
 }  // namespace
 
 // An animation observer to hide the view at the end of the animation.
@@ -426,6 +447,13 @@ void AppListView::InitChildWidgets() {
   search_box_widget_->Init(search_box_widget_params);
   search_box_widget_->SetContentsView(search_box_view_);
 
+#if defined(USE_AURA)
+  // Mouse events on the search box shadow should not be captured.
+  aura::Window* window = search_box_widget_->GetNativeWindow();
+  window->SetEventTargeter(scoped_ptr<ui::EventTargeter>(
+      new SearchBoxWindowTargeter(window, search_box_view_)));
+#endif
+
   app_list_main_view_->contents_view()->Layout();
 }