DevTools: update console viewport scroll when prompt is resized

third_party/WebKit/Source/devtools/front_end/console/ConsolePrompt.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
  */
 Console.ConsolePrompt = class extends UI.Widget {
   constructor() {
     super();
     this._addCompletionsFromHistory = true;
@@ skipping 26 matching lines @@
       delete this._initialText;
       if (this.hasFocus())
         this.focus();
       this.element.tabIndex = -1;
 
       this._editorSetForTest();
     }
   }
 
   /**
+   * @override
+   */
+  onLayout() {
+    this.invalidateSize();

[pfeldman, 2016/12/13 20:06:39]

What is the semantics of this code? When do you get layed out and how can you
request re-layout upon that signal?

[luoe, 2016/12/13 20:29:55]

Semantics are as follows: user changes the height of the prompt by pressing up
to load multiline text from history.  CodeMirrorTextEditor (CMTE)'s "changes"
event fires, and invalidateSize() triggers a chain of onLayout's:
CMTE > ConsolePrompt > SearchableView > ConsoleView

Only CMTE knows when it resizes itself and only ConsoleView knows how to update
its viewport.  Setting up this chain is one way to request the layout.

What this really is is a way to say: 'when the viewport's scrollHeight changes,
update the viewport' without checking differences in scrollHeight.

+  }
+
+  /**
    * @return {!Console.ConsoleHistoryManager}
    */
   history() {
     return this._history;
   }
 
   clearAutocomplete() {
     if (this._editor)
       this._editor.clearAutocomplete();
   }
@@ skipping 300 matching lines @@
     return this._currentHistoryItem();
   }
 
   /**
    * @return {string|undefined}
    */
   _currentHistoryItem() {
     return this._data[this._data.length - this._historyOffset];
   }
 };