[cr-action-menu] Constrain menu to viewport.

ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @typedef {{
  *   top: number,
  *   left: number,
  *   width: (number|undefined),
  *   height: (number|undefined),
@@ skipping 21 matching lines @@
 
 (function() {
 /**
  * Returns the point to start along the X or Y axis given a start and end
  * point to anchor to, the length of the target and the direction to anchor
  * in. If honoring the anchor would force the menu outside of min/max, this
  * will ignore the anchor position and try to keep the menu within min/max.
  * @private
  * @param {number} start
  * @param {number} end
- * @param {number} length
+ * @param {number} menuLength
  * @param {AnchorAlignment} anchorAlignment
  * @param {number} min
  * @param {number} max
  * @return {number}
  */
 function getStartPointWithAnchor(
-    start, end, length, anchorAlignment, min, max) {
+    start, end, menuLength, anchorAlignment, min, max) {
   var startPoint = 0;
   switch (anchorAlignment) {
     case AnchorAlignment.BEFORE_START:
-      startPoint = -length;
+      startPoint = -menuLength;
       break;
     case AnchorAlignment.AFTER_START:
       startPoint = start;
       break;
     case AnchorAlignment.CENTER:
-      startPoint = (start + end - length) / 2;
+      startPoint = (start + end - menuLength) / 2;
       break;
     case AnchorAlignment.BEFORE_END:
-      startPoint = end - length;
+      startPoint = end - menuLength;
       break;
     case AnchorAlignment.AFTER_END:
       startPoint = end;
       break;
   }
 
-  if (startPoint + length > max)
-    startPoint = end - length;
+  if (startPoint + menuLength > max)
+    startPoint = end - menuLength;
   if (startPoint < min)
     startPoint = start;
+
+  startPoint = Math.max(min, Math.min(startPoint, max - menuLength));
+
   return startPoint;
 }
 
 /**
  * @private
  * @return {!ShowConfig}
  */
 function getDefaultShowConfig() {
   return {
     top: 0,
@@ skipping 280 matching lines @@
   addCloseListeners_: function() {
     this.boundClose_ = this.boundClose_ || function() {
       if (this.open)
         this.close();
     }.bind(this);
     window.addEventListener('resize', this.boundClose_);
     window.addEventListener('popstate', this.boundClose_);
   },
 });
 })();