Files.app: Add UI to toggle and clear item selection.

ui/file_manager/file_manager/common/js/util.js

Index: ui/file_manager/file_manager/common/js/util.js
diff --git a/ui/file_manager/file_manager/common/js/util.js b/ui/file_manager/file_manager/common/js/util.js
index 08487e4c9528045c66f30760a86d4bc4d3484eb6..4993ae16fec7cf404016738d51b2323dcfcf46cc 100644
--- a/ui/file_manager/file_manager/common/js/util.js
+++ b/ui/file_manager/file_manager/common/js/util.js
@@ -1029,3 +1029,24 @@ util.addEventListenerToBackgroundComponent = function(target, type, handler) {
     target.removeEventListener(type, handler);
   });
 };
+
+/**
+ * Repeats a given event to a given target with event.ctrlKey set true.
+ * @param {!EventTarget} target Event target which receives the repeated event.
+ * @param {!Event} event Original mouse event.
+ */
+util.repeatMouseEventWithCtrlKey = function(target, event) {
+  event.stopPropagation();
+  event.preventDefault();
+  event = assertInstanceof(event, MouseEvent);
+  var eventWithCtrl = new MouseEvent(event.type, {
+    bubbles: event.bubbles,
+    button: event.button,
+    clientX: event.clientX,
+    clientY: event.clientY,
+    ctrlKey: true,
+    shiftKey: event.shiftKey,
+    target: event.target
+  });
+  target.dispatchEvent(eventWithCtrl);
+};