Hide Vertical Tab strip widget when disabled (#18241)

On Mac, the vertical tab strip widget shows up when restoring the
browser window. This is because upstream implementation makes all
child widgets regardless of their previous visibility.

In order to fix that, observes the widget's visibility and double-check
it should be visible.

browser/ui/views/frame/vertical_tab_strip_widget_delegate_view.cc

@@ -10,6 +10,7 @@
 #include "base/check.h"
 #include "brave/browser/ui/views/frame/brave_browser_view.h"
 #include "brave/browser/ui/views/frame/vertical_tab_strip_region_view.h"
+#include "brave/browser/ui/views/tabs/vertical_tab_utils.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/theme_copying_widget.h"
@@ -134,11 +135,15 @@ VerticalTabStripWidgetDelegateView::VerticalTabStripWidgetDelegateView(
   SetLayoutManager(std::make_unique<views::FillLayout>());
 
   host_view_observation_.Observe(host_);
-  widget_observation_.Observe(host_->GetWidget());
+  widget_observation_.AddObservation(host_->GetWidget());
 
   ChildPreferredSizeChanged(region_view_);
 }
 
+void VerticalTabStripWidgetDelegateView::AddedToWidget() {
+  widget_observation_.AddObservation(GetWidget());
+}
+
 void VerticalTabStripWidgetDelegateView::ChildPreferredSizeChanged(
     views::View* child) {
   if (!host_)
@@ -180,9 +185,27 @@ void VerticalTabStripWidgetDelegateView::OnViewIsDeleting(
   host_ = nullptr;
 }
 
+void VerticalTabStripWidgetDelegateView::OnWidgetVisibilityChanged(
+    views::Widget* widget,
+    bool visible) {
+  if (widget == GetWidget()) {
+    if (!tabs::utils::ShouldShowVerticalTabs(browser_view_->browser()) &&
+        visible) {
+      // This happens when restoring browser window. The upstream implementation
+      // make child widgets visible regardless of their previous visibility.
+      // https://github.com/brave/brave-browser/issues/29917
+      widget->Hide();
+    }
+  }
+}
+
 void VerticalTabStripWidgetDelegateView::OnWidgetBoundsChanged(
     views::Widget* widget,
     const gfx::Rect& new_bounds) {
+  if (widget == GetWidget()) {
+    return;
+  }
+
   // The parent widget could be resized because fullscreen status changed.
   // Try resetting preferred size.
   ChildPreferredSizeChanged(region_view_);
@@ -204,6 +227,8 @@ void VerticalTabStripWidgetDelegateView::UpdateWidgetBounds() {
     return;
   }
 
+  DCHECK(tabs::utils::ShouldShowVerticalTabs(browser_view_->browser()));
+
   auto insets = host_->GetInsets();
   widget_bounds.set_width(widget_bounds.width() + insets.width());
   if (GetInsets() != insets) {
@@ -228,7 +253,7 @@ void VerticalTabStripWidgetDelegateView::UpdateWidgetBounds() {
 
 void VerticalTabStripWidgetDelegateView::OnWidgetDestroying(
     views::Widget* widget) {
-  widget_observation_.Reset();
+  widget_observation_.RemoveObservation(widget);
 }
 
 #if BUILDFLAG(IS_MAC)

browser/ui/views/frame/vertical_tab_strip_widget_delegate_view.h

@@ -8,6 +8,7 @@
 
 #include <memory>
 
+#include "base/scoped_multi_source_observation.h"
 #include "ui/views/view_observer.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/widget_observer.h"
@@ -47,6 +48,7 @@ class VerticalTabStripWidgetDelegateView : public views::WidgetDelegateView,
   }
 
   // views::WidgetDelegateView:
+  void AddedToWidget() override;
   void ChildPreferredSizeChanged(views::View* child) override;
 
   // views::ViewObserver:
@@ -56,6 +58,7 @@ class VerticalTabStripWidgetDelegateView : public views::WidgetDelegateView,
   void OnViewIsDeleting(views::View* observed_view) override;
 
   // views::WidgetObserver:
+  void OnWidgetVisibilityChanged(views::Widget* widget, bool visible) override;
   void OnWidgetBoundsChanged(views::Widget* widget,
                              const gfx::Rect& new_bounds) override;
   void OnWidgetDestroying(views::Widget* widget) override;
@@ -76,7 +79,7 @@ class VerticalTabStripWidgetDelegateView : public views::WidgetDelegateView,
   base::ScopedObservation<views::View, views::ViewObserver>
       host_view_observation_{this};
 
-  base::ScopedObservation<views::Widget, views::WidgetObserver>
+  base::ScopedMultiSourceObservation<views::Widget, views::WidgetObserver>
       widget_observation_{this};
 };