New SELECT Popup: Fix window width to include scrollbar width

Source/web/resources/listPicker.js

 "use strict";
 // Copyright (c) 2014 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.
 
 var global = {
     argumentsReceived: false,
     params: null,
     picker: null
 };
@@ skipping 160 matching lines @@
         window.pagePopupController.setValue(this._selectElement.value);
     }
 };
 
 ListPicker.prototype._fixWindowSize = function() {
     this._selectElement.style.height = "";
     this._selectElement.size = 20;
     var maxHeight = this._selectElement.offsetHeight;
     this._selectElement.style.height = "0";
     var heightOutsideOfContent = this._selectElement.offsetHeight - this._selectElement.clientHeight;
-    var desiredWindowHeight = Math.round(this._calculateScrollHeight() + heightOutsideOfContent);
-    if (desiredWindowHeight > maxHeight)
+    var noScrollHeight = Math.round(this._calculateScrollHeight() + heightOutsideOfContent);
+    var desiredWindowHeight = noScrollHeight;
+    var desiredWindowWidth = this._selectElement.offsetWidth;
+    var expectingScrollbar = false;
+    if (desiredWindowHeight > maxHeight) {
         desiredWindowHeight = maxHeight;
-    var desiredWindowWidth = Math.max(this._config.anchorRectInScreen.width, this._selectElement.offsetWidth);
+        // Setting overflow to auto does not increase width for the scrollbar
+        // so we need to do it manually.
+        desiredWindowWidth += getScrollbarWidth();
+        expectingScrollbar = true;
+    }
+    desiredWindowWidth = Math.max(this._config.anchorRectInScreen.width, desiredWindowWidth);
     var windowRect = adjustWindowRect(desiredWindowWidth, desiredWindowHeight, this._selectElement.offsetWidth, 0);
+    // If the available screen space is smaller than maxHeight, we will get an unexpected scrollbar.
+    if (!expectingScrollbar && windowRect.height < noScrollHeight) {
+        desiredWindowWidth = windowRect.width + getScrollbarWidth();
+        windowRect = adjustWindowRect(desiredWindowWidth, windowRect.height, windowRect.width, windowRect.height);
+    }
     this._selectElement.style.width = windowRect.width + "px";
     this._selectElement.style.height = windowRect.height + "px";
     this._element.style.height = windowRect.height + "px";
     setWindowRect(windowRect);
 };
 
 ListPicker.prototype._calculateScrollHeight = function() {
     // Element.scrollHeight returns an integer value but this calculate the
     // actual fractional value.
     var top = Infinity;
@@ skipping 133 matching lines @@
     }
     this._applyItemStyle(element, config.style);
 };
 
 if (window.dialogArguments) {
     initialize(dialogArguments);
 } else {
     window.addEventListener("message", handleMessage, false);
     window.setTimeout(handleArgumentsTimeout, 1000);
 }