[Devtools] Fixed scrolling in network panel

third_party/WebKit/Source/devtools/front_end/network/NetworkLogViewColumns.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.
 /**
  * @unrestricted
  */
 Network.NetworkLogViewColumns = class {
   /**
    * @param {!Network.NetworkLogView} networkLogView
    * @param {!Network.NetworkTransferTimeCalculator} timeCalculator
@@ skipping 155 matching lines @@
       event.consume(true);
     this._activeScroller.scrollTop -= event.wheelDeltaY;
     this._syncScrollers();
   }
 
   _syncScrollers() {
     if (!this._waterfallColumn.isShowing())
       return;
     this._waterfallScrollerContent.style.height = this._dataGridScroller.scrollHeight + 'px';
     this._updateScrollerWidthIfNeeded();
-    this._dataGridScroller.scrollTop = this._waterfallScroller.scrollTop;
+    var scrollDifference = this._dataGridScroller.scrollTop - this._waterfallScroller.scrollTop;
+    // Ensure we scroll by at least 3 px because of rounding. See: Element.prototype.isScrolledToBottom
+    if (Math.abs(scrollDifference) < 3)
+      scrollDifference = -3;

[luoe, 2017/01/25 17:07:06]

If we check just based on scrollDifference, we may apply this check even when
scrolling a small amount in the middle.  Maybe we only want to do this when
adding the difference would move it too close to the bottom?

var wouldBeCloseToBottom = dataGridScroller.scrollHeight -
(dataGridScroller.scrollTop - scrollDifference) <= 2;
if (wouldBeCloseToBottom) {
    if (scrollDifference < 0) // jump to bottom
    else if (scrolllDifference > 0) // use scrollDifference - 3
}

[allada, 2017/01/25 22:38:54]

Done.

+    this._dataGridScroller.scrollTop -= scrollDifference;
   }
 
   _updateScrollerWidthIfNeeded() {
     if (this._waterfallScrollerWidthIsStale) {
       this._waterfallScrollerWidthIsStale = false;
       this._waterfallColumn.setRightPadding(
           this._waterfallScroller.offsetWidth - this._waterfallScrollerContent.offsetWidth);
     }
   }
 
@@ skipping 616 matching lines @@
 /**
  * @enum {string}
  */
 Network.NetworkLogViewColumns.WaterfallSortIds = {
   StartTime: 'startTime',
   ResponseTime: 'responseReceivedTime',
   EndTime: 'endTime',
   Duration: 'duration',
   Latency: 'latency'
 };