cefclient: views: Add overlay BrowserView demo (see #3790)

Adds new `--show-overlay-browser` command-line flag that creates an
overlay containing an Alloy-style BrowserView.  The main BrowserView
may be Chrome- (default) or Alloy-style (add `--use-alloy-style`).
This overlay will only be added to standalone (non-popup) windows.

Popups triggered via the overlay will receive standard Alloy-style
handling in cefclient (e.g. Views-hosted window). Add
`--use-default-popup` for default popup handling.

cef_paths2.gypi

@@ -288,6 +288,8 @@
       'tests/cefclient/browser/urlrequest_test.h',
       'tests/cefclient/browser/views_menu_bar.cc',
       'tests/cefclient/browser/views_menu_bar.h',
+      'tests/cefclient/browser/views_overlay_browser.cc',
+      'tests/cefclient/browser/views_overlay_browser.h',
       'tests/cefclient/browser/views_overlay_controls.cc',
       'tests/cefclient/browser/views_overlay_controls.h',
       'tests/cefclient/browser/views_style.cc',

libcef/browser/views/browser_view_impl.cc

@@ -280,8 +280,8 @@ void CefBrowserViewImpl::AddedToWidget() {
   CefWidget* cef_widget = CefWidget::GetForWidget(widget);
   DCHECK(cef_widget);
 
-  if (!browser_) {
-    if (cef_widget->IsAlloyStyle() && !is_alloy_style_) {
+  if (!browser_ && !is_alloy_style_) {
+    if (cef_widget->IsAlloyStyle()) {
       LOG(ERROR) << "Cannot add Chrome style BrowserView to Alloy style Window";
       return;
     }

tests/cefclient/browser/default_client_handler.cc

@@ -4,8 +4,16 @@
 
 #include "tests/cefclient/browser/default_client_handler.h"
 
+#include "tests/cefclient/browser/main_context.h"
+#include "tests/cefclient/browser/root_window_manager.h"
+
 namespace client {
 
+DefaultClientHandler::DefaultClientHandler(std::optional<bool> use_alloy_style)
+    : use_alloy_style_(
+          use_alloy_style.value_or(MainContext::Get()->UseAlloyStyleGlobal())) {
+}
+
 // static
 CefRefPtr<DefaultClientHandler> DefaultClientHandler::GetForClient(
     CefRefPtr<CefClient> client) {
@@ -16,4 +24,39 @@ CefRefPtr<DefaultClientHandler> DefaultClientHandler::GetForClient(
   return nullptr;
 }
 
+bool DefaultClientHandler::OnBeforePopup(
+    CefRefPtr<CefBrowser> browser,
+    CefRefPtr<CefFrame> frame,
+    const CefString& target_url,
+    const CefString& target_frame_name,
+    CefLifeSpanHandler::WindowOpenDisposition target_disposition,
+    bool user_gesture,
+    const CefPopupFeatures& popupFeatures,
+    CefWindowInfo& windowInfo,
+    CefRefPtr<CefClient>& client,
+    CefBrowserSettings& settings,
+    CefRefPtr<CefDictionaryValue>& extra_info,
+    bool* no_javascript_access) {
+  CEF_REQUIRE_UI_THREAD();
+
+  if (target_disposition == CEF_WOD_NEW_PICTURE_IN_PICTURE) {
+    // Use default handling for document picture-in-picture popups.
+    client = nullptr;
+    return false;
+  }
+
+  // Used to configure default values.
+  RootWindowConfig config(/*command_line=*/nullptr);
+
+  // Potentially create a new RootWindow for the popup browser that will be
+  // created asynchronously.
+  MainContext::Get()->GetRootWindowManager()->CreateRootWindowAsPopup(
+      config.use_views, use_alloy_style_, config.with_controls,
+      /*is_osr=*/false, /*is_devtools=*/false, popupFeatures, windowInfo,
+      client, settings);
+
+  // Allow popup creation.
+  return false;
+}
+
 }  // namespace client

tests/cefclient/browser/default_client_handler.h

@@ -6,6 +6,8 @@
 #define CEF_TESTS_CEFCLIENT_BROWSER_DEFAULT_CLIENT_HANDLER_H_
 #pragma once
 
+#include <optional>
+
 #include "tests/cefclient/browser/base_client_handler.h"
 
 namespace client {
@@ -14,18 +16,37 @@ namespace client {
 // style only.
 class DefaultClientHandler : public BaseClientHandler {
  public:
-  DefaultClientHandler() = default;
+  // If |use_alloy_style| is nullopt the global default will be used.
+  explicit DefaultClientHandler(
+      std::optional<bool> use_alloy_style = std::nullopt);
 
   // Returns the DefaultClientHandler for |client|, or nullptr if |client| is
   // not a DefaultClientHandler.
   static CefRefPtr<DefaultClientHandler> GetForClient(
       CefRefPtr<CefClient> client);
 
+ protected:
+  bool OnBeforePopup(
+      CefRefPtr<CefBrowser> browser,
+      CefRefPtr<CefFrame> frame,
+      const CefString& target_url,
+      const CefString& target_frame_name,
+      CefLifeSpanHandler::WindowOpenDisposition target_disposition,
+      bool user_gesture,
+      const CefPopupFeatures& popupFeatures,
+      CefWindowInfo& windowInfo,
+      CefRefPtr<CefClient>& client,
+      CefBrowserSettings& settings,
+      CefRefPtr<CefDictionaryValue>& extra_info,
+      bool* no_javascript_access) override;
+
  private:
   // Used to determine the object type.
   virtual const void* GetTypeKey() const override { return &kTypeKey; }
   static constexpr int kTypeKey = 0;
 
+  const bool use_alloy_style_;
+
   IMPLEMENT_REFCOUNTING(DefaultClientHandler);
   DISALLOW_COPY_AND_ASSIGN(DefaultClientHandler);
 };

tests/cefclient/browser/root_window_manager.cc

@@ -134,8 +134,11 @@ scoped_refptr<RootWindow> RootWindowManager::CreateRootWindowAsPopup(
 
   if (MainContext::Get()->UseDefaultPopup() || (is_devtools && !use_views)) {
     // Use default window creation for the popup. A new |client| instance is
-    // still required by cefclient architecture.
-    client = new DefaultClientHandler();
+    // required by cefclient architecture if the type is not already
+    // DefaultClientHandler.
+    if (!DefaultClientHandler::GetForClient(client)) {
+      client = new DefaultClientHandler(use_alloy_style);
+    }
     return nullptr;
   }
 

tests/cefclient/browser/views_overlay_browser.cc

@@ -0,0 +1,102 @@
+// Copyright (c) 2024 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+#include "tests/cefclient/browser/views_overlay_browser.h"
+
+#include "include/views/cef_window.h"
+#include "tests/cefclient/browser/views_window.h"
+
+namespace client {
+
+ViewsOverlayBrowser::ViewsOverlayBrowser(ViewsWindow* owner_window)
+    : owner_window_(owner_window) {}
+
+void ViewsOverlayBrowser::Initialize(
+    CefRefPtr<CefWindow> window,
+    CefRefPtr<CefClient> client,
+    const std::string& url,
+    const CefBrowserSettings& settings,
+    CefRefPtr<CefRequestContext> request_context) {
+  CHECK(!window_);
+  window_ = window;
+  CHECK(window_);
+
+  browser_view_ = CefBrowserView::CreateBrowserView(
+      client, url, settings, nullptr, request_context, this);
+  CHECK(browser_view_);
+
+  controller_ = window_->AddOverlayView(browser_view_, CEF_DOCKING_MODE_CUSTOM,
+                                        /*can_activate=*/true);
+  CHECK(controller_);
+}
+
+void ViewsOverlayBrowser::Destroy() {
+  window_ = nullptr;
+  browser_view_ = nullptr;
+  controller_->Destroy();
+  controller_ = nullptr;
+}
+
+void ViewsOverlayBrowser::UpdateBounds(CefInsets insets) {
+  if (!controller_) {
+    return;
+  }
+
+  // Update location bar size, position and visibility.
+  const auto window_bounds = window_->GetBounds();
+
+  // Client coordinates with insets.
+  CefRect bounds;
+  bounds.x = insets.left;
+  bounds.width = window_bounds.width - insets.left - insets.right;
+  bounds.y = insets.top;
+  bounds.height = window_bounds.height - insets.top - insets.bottom;
+
+  const auto min_size = browser_view_->GetMinimumSize();
+  if (bounds.width < min_size.width || bounds.height < min_size.height) {
+    // Not enough space.
+    controller_->SetVisible(false);
+  } else {
+    controller_->SetSize(CefSize(bounds.width, bounds.height));
+    controller_->SetBounds(bounds);
+    controller_->SetVisible(true);
+  }
+}
+
+void ViewsOverlayBrowser::UpdateDraggableRegions(
+    std::vector<CefDraggableRegion>& window_regions) {
+  if (controller_ && controller_->IsVisible()) {
+    window_regions.emplace_back(controller_->GetBounds(),
+                                /*draggable=*/false);
+  }
+}
+
+CefSize ViewsOverlayBrowser::GetMinimumSize(CefRefPtr<CefView> view) {
+  return CefSize(200, 200);
+}
+
+CefRefPtr<CefBrowserViewDelegate>
+ViewsOverlayBrowser::GetDelegateForPopupBrowserView(
+    CefRefPtr<CefBrowserView> browser_view,
+    const CefBrowserSettings& settings,
+    CefRefPtr<CefClient> client,
+    bool is_devtools) {
+  return owner_window_->GetDelegateForPopupBrowserView(browser_view, settings,
+                                                       client, is_devtools);
+}
+
+bool ViewsOverlayBrowser::OnPopupBrowserViewCreated(
+    CefRefPtr<CefBrowserView> browser_view,
+    CefRefPtr<CefBrowserView> popup_browser_view,
+    bool is_devtools) {
+  return owner_window_->OnPopupBrowserViewCreated(
+      browser_view, popup_browser_view, is_devtools);
+}
+
+cef_runtime_style_t ViewsOverlayBrowser::GetBrowserRuntimeStyle() {
+  // Overlay browser view must always be Alloy style.
+  return CEF_RUNTIME_STYLE_ALLOY;
+}
+
+}  // namespace client

tests/cefclient/browser/views_overlay_browser.h

@@ -0,0 +1,63 @@
+// Copyright (c) 2024 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+#ifndef CEF_TESTS_CEFCLIENT_BROWSER_VIEWS_OVERLAY_BROWSER_H_
+#define CEF_TESTS_CEFCLIENT_BROWSER_VIEWS_OVERLAY_BROWSER_H_
+#pragma once
+
+#include "include/views/cef_browser_view.h"
+#include "include/views/cef_browser_view_delegate.h"
+#include "include/views/cef_overlay_controller.h"
+
+namespace client {
+
+class ViewsWindow;
+
+// Implements a browser view that receives absolute positioning on top of the
+// main browser view. All methods must be called on the browser process UI
+// thread.
+class ViewsOverlayBrowser : public CefBrowserViewDelegate {
+ public:
+  explicit ViewsOverlayBrowser(ViewsWindow* owner_window);
+
+  void Initialize(CefRefPtr<CefWindow> window,
+                  CefRefPtr<CefClient> client,
+                  const std::string& url,
+                  const CefBrowserSettings& settings,
+                  CefRefPtr<CefRequestContext> request_context);
+  void Destroy();
+
+  // Update browser bounds.
+  void UpdateBounds(CefInsets insets);
+
+  // Exclude all regions obscured by overlays.
+  void UpdateDraggableRegions(std::vector<CefDraggableRegion>& window_regions);
+
+ private:
+  // CefViewDelegate methods:
+  CefSize GetMinimumSize(CefRefPtr<CefView> view) override;
+
+  // CefBrowserViewDelegate methods:
+  CefRefPtr<CefBrowserViewDelegate> GetDelegateForPopupBrowserView(
+      CefRefPtr<CefBrowserView> browser_view,
+      const CefBrowserSettings& settings,
+      CefRefPtr<CefClient> client,
+      bool is_devtools) override;
+  bool OnPopupBrowserViewCreated(CefRefPtr<CefBrowserView> browser_view,
+                                 CefRefPtr<CefBrowserView> popup_browser_view,
+                                 bool is_devtools) override;
+  cef_runtime_style_t GetBrowserRuntimeStyle() override;
+
+  ViewsWindow* const owner_window_;
+  CefRefPtr<CefWindow> window_;
+  CefRefPtr<CefBrowserView> browser_view_;
+  CefRefPtr<CefOverlayController> controller_;
+
+  IMPLEMENT_REFCOUNTING(ViewsOverlayBrowser);
+  DISALLOW_COPY_AND_ASSIGN(ViewsOverlayBrowser);
+};
+
+}  // namespace client
+
+#endif  // CEF_TESTS_CEFCLIENT_BROWSER_VIEWS_OVERLAY_BROWSER_H_

tests/cefclient/browser/views_window.cc

@@ -12,6 +12,7 @@
 #include "include/cef_i18n_util.h"
 #include "include/views/cef_box_layout.h"
 #include "include/wrapper/cef_helpers.h"
+#include "tests/cefclient/browser/default_client_handler.h"
 #include "tests/cefclient/browser/main_context.h"
 #include "tests/cefclient/browser/resource.h"
 #include "tests/cefclient/browser/views_style.h"
@@ -146,6 +147,14 @@ CefRefPtr<ViewsWindow> ViewsWindow::Create(
   CefRefPtr<ViewsWindow> views_window =
       new ViewsWindow(type, delegate, nullptr, command_line);
 
+  // Only create an overlay browser for a primary window.
+  if (command_line->HasSwitch(switches::kShowOverlayBrowser)) {
+    views_window->with_overlay_browser_ = true;
+    views_window->initial_url_ = url;
+    views_window->settings_ = settings;
+    views_window->request_context_ = request_context;
+  }
+
   const auto expected_browser_runtime_style = views_window->use_alloy_style_
                                                   ? CEF_RUNTIME_STYLE_ALLOY
                                                   : CEF_RUNTIME_STYLE_CHROME;
@@ -359,6 +368,11 @@ void ViewsWindow::SetDraggableRegions(
     overlay_controls_->UpdateDraggableRegions(window_regions);
   }
 
+  if (overlay_browser_) {
+    // Exclude all regions obscured by overlays.
+    overlay_browser_->UpdateDraggableRegions(window_regions);
+  }
+
   window_->SetDraggableRegions(window_regions);
 }
 
@@ -1001,6 +1015,19 @@ void ViewsWindow::OnWindowChanged(CefRefPtr<CefView> view, bool added) {
                                     CreateLocationBar(),
                                     chrome_toolbar_type_ != CEF_CTT_NONE);
     }
+
+    if (with_overlay_browser_) {
+      overlay_browser_ = new ViewsOverlayBrowser(this);
+
+      // Use default behavior for the overlay browser. A new |client| instance
+      // is still required by cefclient architecture.
+      CefRefPtr<CefClient> client =
+          new DefaultClientHandler(/*use_alloy_style=*/true);
+
+      overlay_browser_->Initialize(window_, client, initial_url_, settings_,
+                                   request_context_);
+      request_context_ = nullptr;
+    }
   } else {
     // Remove any controls that may include the Chrome toolbar before removing
     // the BrowserView.
@@ -1015,6 +1042,10 @@ void ViewsWindow::OnWindowChanged(CefRefPtr<CefView> view, bool added) {
         location_bar_ = nullptr;
       }
     }
+    if (overlay_browser_) {
+      overlay_browser_->Destroy();
+      overlay_browser_ = nullptr;
+    }
   }
 }
 
@@ -1028,6 +1059,12 @@ void ViewsWindow::OnLayoutChanged(CefRefPtr<CefView> view,
   if (overlay_controls_) {
     overlay_controls_->UpdateControls();
   }
+
+  if (overlay_browser_) {
+    // TODO: Consider modifying insets based on toolbar visibility.
+    CefInsets window_insets(200, 200, 200, 200);
+    overlay_browser_->UpdateBounds(window_insets);
+  }
 }
 
 void ViewsWindow::OnThemeChanged(CefRefPtr<CefView> view) {

tests/cefclient/browser/views_window.h

@@ -27,6 +27,7 @@
 #include "tests/cefclient/browser/image_cache.h"
 #include "tests/cefclient/browser/root_window.h"
 #include "tests/cefclient/browser/views_menu_bar.h"
+#include "tests/cefclient/browser/views_overlay_browser.h"
 #include "tests/cefclient/browser/views_overlay_controls.h"
 
 namespace client {
@@ -280,6 +281,13 @@ class ViewsWindow : public CefBrowserViewDelegate,
 
   CefRefPtr<ViewsOverlayControls> overlay_controls_;
 
+  // Overlay browser view state.
+  bool with_overlay_browser_ = false;
+  std::string initial_url_;
+  CefBrowserSettings settings_;
+  CefRefPtr<CefRequestContext> request_context_;
+  CefRefPtr<ViewsOverlayBrowser> overlay_browser_;
+
   std::optional<float> default_titlebar_height_;
   std::optional<float> override_titlebar_height_;
 

tests/shared/common/client_switches.cc

@@ -58,5 +58,6 @@ const char kHideWindowOnClose[] = "hide-window-on-close";
 const char kAcceptsFirstMouse[] = "accepts-first-mouse";
 const char kUseAlloyStyle[] = "use-alloy-style";
 const char kUseChromeStyleWindow[] = "use-chrome-style-window";
+const char kShowOverlayBrowser[] = "show-overlay-browser";
 
 }  // namespace client::switches

tests/shared/common/client_switches.h

@@ -52,6 +52,7 @@ extern const char kHideWindowOnClose[];
 extern const char kAcceptsFirstMouse[];
 extern const char kUseAlloyStyle[];
 extern const char kUseChromeStyleWindow[];
+extern const char kShowOverlayBrowser[];
 
 }  // namespace client::switches