Update text field 'change' event logic to match to Firefox.

third_party/WebKit/Source/core/html/TextControlElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2009, 2010, 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 46 matching lines @@
   // Common flag for HTMLInputElement::tooLong(),
   // HTMLTextAreaElement::tooLong(),
   // HTMLInputElement::tooShort() and HTMLTextAreaElement::tooShort().
   enum NeedsToCheckDirtyFlag { CheckDirtyFlag, IgnoreDirtyFlag };
 
   ~TextControlElement() override;
 
   void forwardEvent(Event*);
 
   void setFocused(bool flag) override;
-  InsertionNotificationRequest insertedInto(ContainerNode*) override;
 
   // The derived class should return true if placeholder processing is needed.
   virtual bool isPlaceholderVisible() const = 0;
   virtual void setPlaceholderVisibility(bool) = 0;
   virtual bool supportsPlaceholder() const = 0;
   String strippedPlaceholder() const;
   HTMLElement* placeholderElement() const;
   void updatePlaceholderVisibility();
 
   VisiblePosition visiblePositionForIndex(int) const;
@@ skipping 27 matching lines @@
   virtual bool supportsAutocapitalize() const = 0;
   virtual const AtomicString& defaultAutocapitalize() const = 0;
   const AtomicString& autocapitalize() const;
   void setAutocapitalize(const AtomicString&);
 
   int maxLength() const;
   int minLength() const;
   void setMaxLength(int, ExceptionState&);
   void setMinLength(int, ExceptionState&);
 
-  // Dispatch 'input' event, and update
-  // m_wasChangedSinceLastFormControlChangeEvent flag.
+  // Dispatch 'input' event.
   void dispatchFormControlInputEvent();
   // Dispatch 'change' event if the value is updated.
   void dispatchFormControlChangeEvent();
   // Enqueue 'change' event if the value is updated.
   void enqueueChangeEvent();
-  void setTextAsOfLastFormControlChangeEvent(const String& text) {
-    m_textAsOfLastFormControlChangeEvent = text;
-  }
-  // A user has changed the value since the last 'change' event.
-  bool wasChangedSinceLastFormControlChangeEvent() const {
-    return m_wasChangedSinceLastFormControlChangeEvent;
-  }
-  void setChangedSinceLastFormControlChangeEvent(bool);
+  // This should be called on every user-input, before the user-input changes
+  // the value.
+  void setValueBeforeFirstUserEditIfNotSet();
+  // This should be called on every user-input, after the user-input changed the
+  // value. The argument is the updated value.
+  void checkIfValueWasReverted(const String&);
+  void clearValueBeforeFirstUserEdit();
 
   virtual String value() const = 0;
   virtual void setValue(
       const String&,
       TextFieldEventBehavior = DispatchNoEvent,
       TextControlSetValueSelection =
           TextControlSetValueSelection::kSetSelectionToEnd) = 0;
 
   HTMLElement* innerEditorElement() const;
 
@@ skipping 50 matching lines @@
   virtual bool isEmptySuggestedValue() const { return true; }
   // Called in dispatchFocusEvent(), after placeholder process, before calling
   // parent's dispatchFocusEvent().
   virtual void handleFocusEvent(Element* /* oldFocusedNode */, WebFocusType) {}
   // Called in dispatchBlurEvent(), after placeholder process, before calling
   // parent's dispatchBlurEvent().
   virtual void handleBlurEvent() {}
 
   bool placeholderShouldBeVisible() const;
 
-  String m_textAsOfLastFormControlChangeEvent;
-  bool m_wasChangedSinceLastFormControlChangeEvent = false;
+  // In m_valueBeforeFirstUserEdit, we distinguish a null String and zero-length
+  // String. Null String means the field doesn't have any data yet, and
+  // zero-length String is a valid data.
+  String m_valueBeforeFirstUserEdit;
   bool m_lastChangeWasUserEdit;
 
   unsigned m_cachedSelectionStart;
   unsigned m_cachedSelectionEnd;
   TextFieldSelectionDirection m_cachedSelectionDirection;
 
   FRIEND_TEST_ALL_PREFIXES(TextControlElementTest, IndexForPosition);
 };
 
 inline bool isTextControlElement(const Element& element) {
   return element.isTextControl();
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(TextControlElement);
 
 TextControlElement* enclosingTextControl(const Position&);
 TextControlElement* enclosingTextControl(const Node*);
 
 }  // namespace blink
 
 #endif