Cleanup of the code around the upload button of file upload control

* Add HTMLInputElement::UploadButton() to return a shadow element

* Update its active state for CanReceiveDroppedFiles() immediately.
  Remove LayoutFileUploadControl::can_receive_dropped_files_.

* Remove LayoutFileUploadControl::ButtonValue(), which was not used.

* Remove LayoutFileUploadControl::UploadButtonWidth(), which was not defined.

This CL has no behavior changes.

Bug: 1040828
Change-Id: Id2a598dacd9f60451614d38fba3785cea1ec4d92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2000280Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#731846}

third_party/blink/renderer/core/html/forms/file_input_type.cc

@@ -326,25 +326,27 @@ void FileInputType::CreateShadowSubtree() {
           GetElement().Multiple() ? IDS_FORM_MULTIPLE_FILES_BUTTON_LABEL
                                   : IDS_FORM_FILE_BUTTON_LABEL)));
   button->SetShadowPseudoId(AtomicString("-webkit-file-upload-button"));
+  button->SetActive(GetElement().CanReceiveDroppedFiles());
   GetElement().UserAgentShadowRoot()->AppendChild(button);
 }
 
+HTMLInputElement* FileInputType::UploadButton() const {
+  Node* node = GetElement().UserAgentShadowRoot()->firstChild();
+  CHECK(!node || IsA<HTMLInputElement>(node));
+  return To<HTMLInputElement>(node);
+}
+
 void FileInputType::DisabledAttributeChanged() {
   DCHECK(IsShadowHost(GetElement()));
-  CHECK(!GetElement().UserAgentShadowRoot()->firstChild() ||
-        IsA<Element>(GetElement().UserAgentShadowRoot()->firstChild()));
-  if (Element* button =
-          To<Element>(GetElement().UserAgentShadowRoot()->firstChild()))
+  if (Element* button = UploadButton()) {
     button->SetBooleanAttribute(html_names::kDisabledAttr,
                                 GetElement().IsDisabledFormControl());
+  }
 }
 
 void FileInputType::MultipleAttributeChanged() {
   DCHECK(IsShadowHost(GetElement()));
-  CHECK(!GetElement().UserAgentShadowRoot()->firstChild() ||
-        IsA<Element>(GetElement().UserAgentShadowRoot()->firstChild()));
-  if (Element* button =
-          To<Element>(GetElement().UserAgentShadowRoot()->firstChild())) {
+  if (Element* button = UploadButton()) {
     button->setAttribute(
         html_names::kValueAttr,
         AtomicString(GetLocale().QueryString(

third_party/blink/renderer/core/html/forms/file_input_type.h

@@ -88,6 +88,7 @@ class CORE_EXPORT FileInputType final : public InputType,
   bool ReceiveDroppedFiles(const DragData*) override;
   String DroppedFileSystemId() override;
   void CreateShadowSubtree() override;
+  HTMLInputElement* UploadButton() const override;
   void DisabledAttributeChanged() override;
   void MultipleAttributeChanged() override;
   String DefaultToolTip(const InputTypeView&) const override;

third_party/blink/renderer/core/html/forms/html_input_element.cc

@@ -1538,8 +1538,12 @@ void HTMLInputElement::SetCanReceiveDroppedFiles(
   if (!!can_receive_dropped_files_ == can_receive_dropped_files)
     return;
   can_receive_dropped_files_ = can_receive_dropped_files;
-  if (GetLayoutObject())
-    GetLayoutObject()->UpdateFromElement();
+  if (HTMLInputElement* button = UploadButton())
+    button->SetActive(can_receive_dropped_files);
+}
+
+HTMLInputElement* HTMLInputElement::UploadButton() const {
+  return input_type_view_->UploadButton();
 }
 
 String HTMLInputElement::SanitizeValue(const String& proposed_value) const {

third_party/blink/renderer/core/html/forms/html_input_element.h

@@ -235,6 +235,10 @@ class CORE_EXPORT HTMLInputElement
   bool CanReceiveDroppedFiles() const;
   void SetCanReceiveDroppedFiles(bool);
 
+  // Returns 'Choose File(s)' button in a file control. This returns
+  // nullptr for other input types.
+  HTMLInputElement* UploadButton() const;
+
   void OnSearch();
 
   void UpdateClearButtonVisibility();

third_party/blink/renderer/core/html/forms/input_type_view.cc

@@ -128,6 +128,10 @@ void InputTypeView::DestroyShadowSubtree() {
     root->RemoveChildren();
 }
 
+HTMLInputElement* InputTypeView::UploadButton() const {
+  return nullptr;
+}
+
 void InputTypeView::AltAttributeChanged() {}
 
 void InputTypeView::SrcAttributeChanged() {}

third_party/blink/renderer/core/html/forms/input_type_view.h

@@ -106,9 +106,14 @@ class CORE_EXPORT InputTypeView : public GarbageCollectedMixin {
   virtual TextDirection ComputedTextDirection();
   virtual void StartResourceLoading();
   virtual void ClosePopupView();
+
+  // Functions for shadow trees
+
   virtual bool NeedsShadowSubtree() const;
   virtual void CreateShadowSubtree();
   virtual void DestroyShadowSubtree();
+  virtual HTMLInputElement* UploadButton() const;
+
   virtual void MinOrMaxAttributeChanged();
   virtual void StepAttributeChanged();
   virtual void AltAttributeChanged();

third_party/blink/renderer/core/layout/layout_file_upload_control.cc

@@ -39,8 +39,7 @@ const int kDefaultWidthNumChars = 34;
 const int kButtonShadowHeight = 2;
 
 LayoutFileUploadControl::LayoutFileUploadControl(HTMLInputElement* input)
-    : LayoutBlockFlow(input),
-      can_receive_dropped_files_(input->CanReceiveDroppedFiles()) {}
+    : LayoutBlockFlow(input) {}
 
 LayoutFileUploadControl::~LayoutFileUploadControl() = default;
 
@@ -48,14 +47,6 @@ void LayoutFileUploadControl::UpdateFromElement() {
   auto* input = To<HTMLInputElement>(GetNode());
   DCHECK_EQ(input->type(), input_type_names::kFile);
 
-  if (HTMLInputElement* button = UploadButton()) {
-    bool new_can_receive_dropped_files_state = input->CanReceiveDroppedFiles();
-    if (can_receive_dropped_files_ != new_can_receive_dropped_files_state) {
-      can_receive_dropped_files_ = new_can_receive_dropped_files_state;
-      button->SetActive(new_can_receive_dropped_files_state);
-    }
-  }
-
   // This only supports clearing out the files, but that's OK because for
   // security reasons that's the only change the DOM is allowed to make.
   FileList* files = input->files();
@@ -159,18 +150,7 @@ PositionWithAffinity LayoutFileUploadControl::PositionForPoint(
 }
 
 HTMLInputElement* LayoutFileUploadControl::UploadButton() const {
-  // FIXME: This should be on HTMLInputElement as an API like
-  // innerButtonElement().
-  auto* input = To<HTMLInputElement>(GetNode());
-  return DynamicTo<HTMLInputElement>(
-      input->UserAgentShadowRoot()->firstChild());
-}
-
-String LayoutFileUploadControl::ButtonValue() {
-  if (HTMLInputElement* button = UploadButton())
-    return button->value();
-
-  return String();
+  return To<HTMLInputElement>(GetNode())->UploadButton();
 }
 
 String LayoutFileUploadControl::FileTextValue() const {

third_party/blink/renderer/core/layout/layout_file_upload_control.h

@@ -44,11 +44,9 @@ class CORE_EXPORT LayoutFileUploadControl final : public LayoutBlockFlow {
            LayoutBlockFlow::IsOfType(type);
   }
 
-  String ButtonValue();
   String FileTextValue() const;
 
   HTMLInputElement* UploadButton() const;
-  int UploadButtonWidth();
 
   bool HasControlClip() const override { return true; }
   PhysicalRect ControlClipRect(const PhysicalOffset&) const override;
@@ -75,8 +73,6 @@ class CORE_EXPORT LayoutFileUploadControl final : public LayoutBlockFlow {
   int MaxFilenameWidth() const;
 
   PositionWithAffinity PositionForPoint(const PhysicalOffset&) const override;
-
-  bool can_receive_dropped_files_;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutFileUploadControl, IsFileUploadControl());