Fixed cursor is not changed to resize when hovered to sidebar resize area

fix brave/brave-browser#43507

On macOS, previous cursor is not cleared when mouse goes out.
So, we can see resize cursor only once. To fix, clear current cursor
manually. Widget doesn't change its current cursor if it's same with
requested one.

Author: simonhong

browser/ui/views/side_panel/brave_side_panel_resize_widget.cc

@@ -9,6 +9,8 @@
 
 #include "brave/browser/ui/views/frame/brave_browser_view.h"
 #include "brave/browser/ui/views/side_panel/brave_side_panel.h"
+#include "build/build_config.h"
+#include "ui/base/metadata/metadata_impl_macros.h"
 #include "ui/views/controls/resize_area.h"
 #include "ui/views/layout/fill_layout.h"
 #include "ui/views/widget/widget.h"
@@ -18,6 +20,31 @@
 #include "ui/views/view_constants_aura.h"
 #endif
 
+#if BUILDFLAG(IS_MAC)
+namespace {
+
+// Subclassed to clear resize cursor when goes out.
+// On macOS, it seems not clear widget's current cursor(resize) when mouse goes
+// out. Because of that, cursor is not changed when mouse moves in. As this
+// resize widget is located over the Maybe this problem happens because it's
+// located above WebView.
+class CustomResizeArea : public views::ResizeArea {
+  METADATA_HEADER(CustomResizeArea, views::ResizeArea)
+ public:
+  using ResizeArea::ResizeArea;
+
+  void OnMouseExited(const ui::MouseEvent& event) override {
+    ResizeArea::OnMouseExited(event);
+    GetWidget()->SetCursor(ui::Cursor());
+  }
+};
+
+BEGIN_METADATA(CustomResizeArea)
+END_METADATA
+
+}  // namespace
+#endif
+
 SidePanelResizeWidget::SidePanelResizeWidget(
     BraveSidePanel* panel,
     BraveBrowserView* browser_view,
@@ -38,8 +65,13 @@ SidePanelResizeWidget::SidePanelResizeWidget(
   params.activatable = views::Widget::InitParams::Activatable::kNo;
   widget_->Init(std::move(params));
 
-  auto resize_area = std::make_unique<views::ResizeArea>(resize_area_delegate);
-  widget_->SetContentsView(std::move(resize_area));
+#if BUILDFLAG(IS_MAC)
+  widget_->SetContentsView(
+      std::make_unique<CustomResizeArea>(resize_area_delegate));
+#else
+  widget_->SetContentsView(
+      std::make_unique<views::ResizeArea>(resize_area_delegate));
+#endif
 
 #if defined(USE_AURA)
   widget_->GetNativeView()->SetProperty(views::kHostViewKey,