fix: WCO buttons hidden on Linux in fullscreen (#44643)

Closes https://github.com/electron/electron/issues/44569.

Fixes an issue where the WCO buttons were hidden on Linux in  fullscreen mode
but not on Windows or macOS. The Windows behavior is the expected one, so this
commit makes the Linux behavior consistent.

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Shelley Vohr <[email protected]>

shell/browser/ui/views/opaque_frame_view.cc

@@ -256,14 +256,17 @@ void OpaqueFrameView::LayoutWindowControls() {
   buttons_not_shown.push_back(views::FrameButton::kMinimize);
   buttons_not_shown.push_back(views::FrameButton::kClose);
 
-  for (const auto& button : leading_buttons_) {
-    ConfigureButton(button, ALIGN_LEADING);
-    std::erase(buttons_not_shown, button);
-  }
+  // We do not want to show the buttons in fullscreen mode.
+  if (!frame()->IsFullscreen()) {
+    for (const auto& button : leading_buttons_) {
+      ConfigureButton(button, ALIGN_LEADING);
+      std::erase(buttons_not_shown, button);
+    }
 
-  for (const auto& button : base::Reversed(trailing_buttons_)) {
-    ConfigureButton(button, ALIGN_TRAILING);
-    std::erase(buttons_not_shown, button);
+    for (const auto& button : base::Reversed(trailing_buttons_)) {
+      ConfigureButton(button, ALIGN_TRAILING);
+      std::erase(buttons_not_shown, button);
+    }
   }
 
   for (const auto& button_id : buttons_not_shown)
@@ -402,8 +405,7 @@ void OpaqueFrameView::ConfigureButton(views::FrameButton button_id,
                                       ButtonAlignment alignment) {
   switch (button_id) {
     case views::FrameButton::kMinimize: {
-      bool can_minimize = true;  // delegate_->CanMinimize();
-      if (can_minimize) {
+      if (window()->IsMinimizable()) {
         minimize_button_->SetVisible(true);
         SetBoundsForButton(button_id, minimize_button_, alignment);
       } else {
@@ -412,8 +414,7 @@ void OpaqueFrameView::ConfigureButton(views::FrameButton button_id,
       break;
     }
     case views::FrameButton::kMaximize: {
-      bool can_maximize = true;  // delegate_->CanMaximize();
-      if (can_maximize) {
+      if (window()->IsMaximizable()) {
         // When the window is restored, we show a maximized button; otherwise,
         // we show a restore button.
         bool is_restored = !window()->IsMaximized() && !window()->IsMinimized();
@@ -431,8 +432,12 @@ void OpaqueFrameView::ConfigureButton(views::FrameButton button_id,
       break;
     }
     case views::FrameButton::kClose: {
-      close_button_->SetVisible(true);
-      SetBoundsForButton(button_id, close_button_, alignment);
+      if (window()->IsClosable()) {
+        close_button_->SetVisible(true);
+        SetBoundsForButton(button_id, close_button_, alignment);
+      } else {
+        HideButton(button_id);
+      }
       break;
     }
   }