Add builder and metadata to HomeButton

Allow builder and metadata access to HomeButton class.

Bug: 1130078
Change-Id: Idbe96f4888b9fb77406efbafbe2d04110f7ea8f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2450848
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816826}

chrome/browser/ui/views/toolbar/home_button.cc

@@ -23,6 +23,7 @@
 #include "ui/views/bubble/bubble_dialog_delegate_view.h"
 #include "ui/views/controls/styled_label.h"
 #include "ui/views/layout/fill_layout.h"
+#include "ui/views/metadata/metadata_impl_macros.h"
 #include "ui/views/widget/widget.h"
 
 // HomePageUndoBubble --------------------------------------------------------
@@ -88,6 +89,7 @@ HomePageUndoBubble::HomePageUndoBubble(
       browser_(browser),
       undo_value_is_ntp_(undo_value_is_ntp),
       undo_url_(undo_url) {
+  DCHECK(browser_);
   SetButtons(ui::DIALOG_BUTTON_NONE);
   set_margins(
       ChromeLayoutProvider::Get()->GetInsetsMetric(views::INSETS_DIALOG));
@@ -155,10 +157,6 @@ HomeButton::HomeButton(PressedCallback callback, Browser* browser)
 HomeButton::~HomeButton() {
 }
 
-const char* HomeButton::GetClassName() const {
-  return "HomeButton";
-}
-
 bool HomeButton::GetDropFormats(
     int* formats,
     std::set<ui::ClipboardFormatType>* format_types) {
@@ -175,6 +173,9 @@ int HomeButton::OnDragUpdated(const ui::DropTargetEvent& event) {
 }
 
 int HomeButton::OnPerformDrop(const ui::DropTargetEvent& event) {
+  if (!browser_)
+    return ui::DragDropTypes::DRAG_NONE;
+
   GURL new_homepage_url;
   base::string16 title;
   if (event.data().GetURLAndTitle(ui::FilenameToURLPolicy::CONVERT_FILENAMES,
@@ -198,3 +199,6 @@ void HomeButton::UpdateIcon() {
                                           : kNavigateHomeIcon;
   UpdateIconsWithStandardColors(home_image);
 }
+
+BEGIN_METADATA(HomeButton, ToolbarButton)
+END_METADATA

chrome/browser/ui/views/toolbar/home_button.h

@@ -7,18 +7,22 @@
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/ui/views/toolbar/toolbar_button.h"
+#include "ui/views/metadata/metadata_header_macros.h"
+#include "ui/views/metadata/view_factory.h"
 
 class Browser;
 
 class HomeButton : public ToolbarButton {
  public:
-  HomeButton(PressedCallback callback, Browser* browser);
+  METADATA_HEADER(HomeButton);
+
+  explicit HomeButton(PressedCallback callback = PressedCallback(),
+                      Browser* browser = nullptr);
   HomeButton(const HomeButton&) = delete;
   HomeButton& operator=(const HomeButton&) = delete;
   ~HomeButton() override;
 
   // ToolbarButton:
-  const char* GetClassName() const override;
   bool GetDropFormats(int* formats,
                       std::set<ui::ClipboardFormatType>* format_types) override;
   bool CanDrop(const OSExchangeData& data) override;
@@ -30,4 +34,7 @@ class HomeButton : public ToolbarButton {
   Browser* const browser_;
 };
 
+BEGIN_VIEW_BUILDER(/* no export */, HomeButton, ToolbarButton)
+END_VIEW_BUILDER(/* no export */, HomeButton)
+
 #endif  // CHROME_BROWSER_UI_VIEWS_TOOLBAR_HOME_BUTTON_H_