Refactor scroll updates during flexbox layout.

third_party/WebKit/Source/web/resources/listPicker.js

Index: third_party/WebKit/Source/web/resources/listPicker.js
diff --git a/third_party/WebKit/Source/web/resources/listPicker.js b/third_party/WebKit/Source/web/resources/listPicker.js
index 0e25f1ce4329b65262136c01622f26a96dad4ad2..efc8d0c8eb9e2c1830cc4e329764b54b7935ce13 100644
--- a/third_party/WebKit/Source/web/resources/listPicker.js
+++ b/third_party/WebKit/Source/web/resources/listPicker.js
@@ -221,7 +221,6 @@ ListPicker.prototype._fixWindowSize = function() {
     var zoom = this._config.zoomFactor;
     var maxHeight = this._selectElement.offsetHeight * zoom;
     var noScrollHeight = (this._calculateScrollHeight() + ListPicker.ListboxSelectBorder * 2) * zoom;
-    var scrollbarWidth = getScrollbarWidth() * zoom;
     var elementOffsetWidth = this._selectElement.offsetWidth * zoom;
     var desiredWindowHeight = noScrollHeight;
     var desiredWindowWidth = elementOffsetWidth;
@@ -230,14 +229,13 @@ ListPicker.prototype._fixWindowSize = function() {
         desiredWindowHeight = maxHeight;
         // Setting overflow to auto does not increase width for the scrollbar
         // so we need to do it manually.
-        desiredWindowWidth += scrollbarWidth;
         expectingScrollbar = true;
     }
     desiredWindowWidth = Math.max(this._config.anchorRectInScreen.width, desiredWindowWidth);
     var windowRect = adjustWindowRect(desiredWindowWidth, desiredWindowHeight, elementOffsetWidth, 0);
     // If the available screen space is smaller than maxHeight, we will get an unexpected scrollbar.
     if (!expectingScrollbar && windowRect.height < noScrollHeight) {
-        desiredWindowWidth = windowRect.width + scrollbarWidth;
+        desiredWindowWidth = windowRect.width;
         windowRect = adjustWindowRect(desiredWindowWidth, windowRect.height, windowRect.width, windowRect.height);
     }
     this._selectElement.style.width = (windowRect.width / zoom) + "px";