Force close browsers and handle bigpicture exit

Call CloseBrowser(true) for chrome, popup and tab browsers to force shutdown. Immediately destroy the top-level window and call MaybeFinishShutdown() to avoid hangs when WM_CLOSE is not resent by Alloy child-window paths. Route "close" and new "exit-bigpicture" chrome commands through OnWindowCloseRequested so they trigger the same shutdown flow. Add IsBigPictureFrame and permit the "exit-bigpicture" process message from bigpicture internal frames.

src/app/nebula_controller.cpp

@@ -162,10 +162,6 @@ void NebulaController::OnWindowCloseRequested() {
     }
 
     if (closing_) {
-        // CEF re-sends WM_CLOSE to the top-level window after each Alloy
-        // child browser finishes its JS unload + DoClose phase. Destroy the
-        // Nebula window now so CEF can tear down the child browser HWNDs and
-        // fire OnBeforeClose; MaybeFinishShutdown will then quit the loop.
         if (window_ && window_->native_handle()) {
             nebula::platform::DestroyTopLevelWindow(window_->native_handle());
         }
@@ -180,16 +176,24 @@ void NebulaController::OnWindowCloseRequested() {
     }
 
     if (chrome_browser_) {
-        chrome_browser_->GetHost()->CloseBrowser(false);
+        chrome_browser_->GetHost()->CloseBrowser(true);
     }
     if (menu_popup_browser_) {
-        menu_popup_browser_->GetHost()->CloseBrowser(false);
+        menu_popup_browser_->GetHost()->CloseBrowser(true);
     }
     for (const auto& tab : tabs_.Tabs()) {
         if (tab.browser) {
-            tab.browser->GetHost()->CloseBrowser(false);
+            tab.browser->GetHost()->CloseBrowser(true);
         }
     }
+
+    // Do not wait for CEF to re-send WM_CLOSE to the host window. On some
+    // Alloy child-window paths that message never arrives, leaving the app
+    // alive with all close affordances disabled until the process is killed.
+    if (window_ && window_->native_handle()) {
+        nebula::platform::DestroyTopLevelWindow(window_->native_handle());
+    }
+    MaybeFinishShutdown();
 }
 
 void NebulaController::OnActiveTabChanged(const nebula::browser::NebulaTab& tab) {
@@ -307,7 +311,9 @@ void NebulaController::OnChromeCommand(const std::string& command, const std::st
     } else if (command == "maximize" && window_) {
         window_->ToggleMaximize();
     } else if (command == "close" && window_) {
-        window_->Close();
+        OnWindowCloseRequested();
+    } else if (command == "exit-bigpicture" && window_) {
+        OnWindowCloseRequested();
     } else if (command == "drag" && window_) {
         window_->BeginDrag();
     }

src/cef/browser_client.cpp

@@ -25,6 +25,16 @@ bool IsSettingsFrame(CefRefPtr<CefFrame> frame) {
     return nebula::ui::ToInternalUrl(frame->GetURL().ToString()).starts_with("nebula://settings");
 }
 
+bool IsBigPictureFrame(CefRefPtr<CefFrame> frame) {
+    if (!frame) {
+        return false;
+    }
+
+    const std::string url = nebula::ui::ToInternalUrl(frame->GetURL().ToString());
+    return url.starts_with("nebula://bigpicture") ||
+           url.starts_with("nebula://big-picture");
+}
+
 std::vector<std::string> ToStringVector(const std::vector<CefString>& values) {
     std::vector<std::string> result;
     result.reserve(values.size());
@@ -67,7 +77,10 @@ bool NebulaBrowserClient::OnProcessMessageReceived(CefRefPtr<CefBrowser> browser
                                        command == "new-tab" ||
                                        command == "clear-site-history" ||
                                        command == "clear-search-history");
-        if (!allowed_insecure_command && !allowed_settings_command) {
+        const bool allowed_big_picture_command =
+            IsBigPictureFrame(frame) && command == "exit-bigpicture";
+        if (!allowed_insecure_command && !allowed_settings_command &&
+            !allowed_big_picture_command) {
             return false;
         }
     }