DevTools: clicking in console messages should not jump to bottom

third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js

 /*
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 289 matching lines @@
    * @override
    */
   wasShown() {
     this._viewport.refresh();
   }
 
   /**
    * @override
    */
   focus() {
-    if (this._prompt.hasFocus())
-      return;
-    // Set caret position before setting focus in order to avoid scrolling
-    // by focus().
-    this._prompt.moveCaretToEndOfPrompt();
-    this._prompt.focus();
+    if (!this._prompt.hasFocus())
+      this._prompt.focus();

[pfeldman, 2017/04/25 18:50:17]

I think we still reset scroll position here, not?

[luoe, 2017/04/25 23:00:34]

No, only the moveCaretToEndOfPrompt did.

   }
 
   /**
    * @override
    */
   restoreScrollPositions() {
     if (this._viewport.stickToBottom())
       this._immediatelyScrollToBottom();
     else
       super.restoreScrollPositions();
@@ skipping 333 matching lines @@
     this._updateFilterStatus();
     this._searchableView.updateSearchMatchesCount(this._regexMatchRanges.length);
     this._viewport.invalidate();
   }
 
   /**
    * @param {!Event} event
    */
   _messagesClicked(event) {
     var targetElement = event.deepElementFromPoint();
-    if (!targetElement || targetElement.isComponentSelectionCollapsed())
+    if (!targetElement || targetElement.isComponentSelectionCollapsed()) {
       this.focus();
+
+      // Restore scroll position, since moving caret may trigger scroll.
+      var top = this._messagesElement.scrollTop;
+      this._prompt.moveCaretToEndOfPrompt();

[pfeldman, 2017/04/25 18:50:17]

Why moving caret to end of prompt is necessary?

[luoe, 2017/04/25 23:00:34]

Please see above.

+      this._messagesElement.scrollTop = top;
+    }
     var groupMessage = event.target.enclosingNodeOrSelfWithClass('console-group-title');
     if (!groupMessage)
       return;
     var consoleGroupViewMessage = groupMessage.parentElement.message;
     consoleGroupViewMessage.setCollapsed(!consoleGroupViewMessage.collapsed());
     this._updateMessageList();
   }
 
   _registerShortcuts() {
     this._shortcuts = {};
@@ skipping 591 matching lines @@
         return true;
     }
     return false;
   }
 };
 
 /**
  * @typedef {{messageIndex: number, matchIndex: number}}
  */
 Console.ConsoleView.RegexMatchRange;