cefclient: views: Add ability to pop out the overlay Browser (see #3790)

When running with the overlay Browser enabled (`--show-overlay-browser`),
pressing Alt+O will move the overlay Browser to a new top-level Window.
Pressing Alt+O again or closing the new Window via the close button will
return the Browser to the overlay. Closing the Browser via `window.close()`
(in the new Window or overlay) will dismiss the overlay completely as
required to maintain consistent internal state. Detection of this state is
supported by the new CefBrowserHost::IsReadyToBeClosed method.

Draggable regions in the main Browser are updated to account for the
presence or absence of the overlay Browser. Support for draggable regions
in the overlay Browser in not implemented in cefclient.

Behavior with multiple overlays, `window.close()` and draggable regions
can be tested by adding `--hide-frame --hide-controls`.

libcef/browser/browser_platform_delegate.cc

@@ -63,6 +63,10 @@ class PopupWindowDelegate : public CefWindowDelegate {
     return true;
   }
 
+  cef_runtime_style_t GetWindowRuntimeStyle() override {
+    return browser_view_->GetRuntimeStyle();
+  }
+
  private:
   CefRefPtr<CefBrowserView> browser_view_;
 

tests/cefclient/browser/resource.h

@@ -21,6 +21,7 @@
 #define IDC_NAV_STOP 203
 #define ID_QUIT 32500
 #define ID_FIND 32501
+#define ID_POPOUT_OVERLAY 32502
 #define ID_TESTS_FIRST 32700
 #define ID_TESTS_GETSOURCE 32700
 #define ID_TESTS_GETTEXT 32701

tests/cefclient/browser/views_overlay_browser.cc

@@ -5,10 +5,111 @@
 #include "tests/cefclient/browser/views_overlay_browser.h"
 
 #include "include/views/cef_window.h"
+#include "tests/cefclient/browser/resource.h"
 #include "tests/cefclient/browser/views_window.h"
 
 namespace client {
 
+namespace {
+
+void AddPopOutAccelerator(CefRefPtr<CefWindow> window) {
+  // Add an accelerator to toggle the BrowserView popout. OnAccelerator will be
+  // called when the accelerator is triggered.
+  window->SetAccelerator(ID_POPOUT_OVERLAY, 'O', /*shift_pressed=*/false,
+                         /*ctrl_pressed=*/false, /*alt_pressed=*/true,
+                         /*high_priority=*/true);
+}
+
+// Popout window delegate implementation.
+class PopoutWindowDelegate : public CefWindowDelegate {
+ public:
+  PopoutWindowDelegate(base::WeakPtr<ViewsOverlayBrowser> overlay,
+                       CefRefPtr<CefBrowserView> browser_view)
+      : overlay_(overlay), browser_view_(browser_view) {}
+
+  PopoutWindowDelegate(const PopoutWindowDelegate&) = delete;
+  PopoutWindowDelegate& operator=(const PopoutWindowDelegate&) = delete;
+
+  static PopoutWindowDelegate* GetForWindow(CefRefPtr<CefWindow> window) {
+    return static_cast<PopoutWindowDelegate*>(window->GetDelegate().get());
+  }
+
+  void OnWindowCreated(CefRefPtr<CefWindow> window) override {
+    window->AddChildView(browser_view_);
+    window->Show();
+
+    // Add the popout accelerator to the popout Window.
+    AddPopOutAccelerator(window);
+
+    browser_view_->RequestFocus();
+  }
+
+  bool CanClose(CefRefPtr<CefWindow> window) override {
+    CefRefPtr<CefBrowser> browser =
+        browser_view_ ? browser_view_->GetBrowser() : nullptr;
+
+    if (overlay_ && browser && !browser->GetHost()->IsReadyToBeClosed()) {
+      // Proceed with the window close, but don't close the browser. The browser
+      // will be returned to the overlay in OnWindowClosing().
+      return_to_overlay_ = true;
+      return true;
+    }
+
+    if (browser) {
+      // We must close the browser, either because the popout Window is the
+      // final owner of the BrowserView, or because the browser is ready to be
+      // closed internally (e.g. `window.close()` was called).
+      return browser->GetHost()->TryCloseBrowser();
+    }
+
+    return true;
+  }
+
+  void OnWindowClosing(CefRefPtr<CefWindow> window) override {
+    if (overlay_ && return_to_overlay_) {
+      // Give the browser back to the overlay.
+      overlay_->ToggleBrowserView();
+    }
+  }
+
+  void OnWindowDestroyed(CefRefPtr<CefWindow> window) override {
+    if (overlay_) {
+      overlay_->PopOutWindowDestroyed();
+      overlay_ = nullptr;
+    }
+    browser_view_ = nullptr;
+  }
+
+  cef_runtime_style_t GetWindowRuntimeStyle() override {
+    return browser_view_->GetRuntimeStyle();
+  }
+
+  bool OnAccelerator(CefRefPtr<CefWindow> window, int command_id) override {
+    if (overlay_) {
+      return overlay_->OnAccelerator(window, command_id);
+    }
+    return false;
+  }
+
+  [[nodiscard]] CefRefPtr<CefBrowserView> DetachBrowserView() {
+    overlay_ = nullptr;
+    auto browser_view = browser_view_;
+    browser_view_ = nullptr;
+    return browser_view;
+  }
+
+  void OverlayDestroyed() { overlay_ = nullptr; }
+
+ private:
+  base::WeakPtr<ViewsOverlayBrowser> overlay_;
+  CefRefPtr<CefBrowserView> browser_view_;
+  bool return_to_overlay_ = false;
+
+  IMPLEMENT_REFCOUNTING(PopoutWindowDelegate);
+};
+
+}  // namespace
+
 ViewsOverlayBrowser::ViewsOverlayBrowser(ViewsWindow* owner_window)
     : owner_window_(owner_window) {}
 
@@ -22,10 +123,14 @@ void ViewsOverlayBrowser::Initialize(
   window_ = window;
   CHECK(window_);
 
+  // Add the accelerator to the main window.
+  AddPopOutAccelerator(window_);
+
   browser_view_ = CefBrowserView::CreateBrowserView(
       client, url, settings, nullptr, request_context, this);
   CHECK(browser_view_);
 
+  // Add the BrowserView to an overlay in the main window.
   controller_ = window_->AddOverlayView(browser_view_, CEF_DOCKING_MODE_CUSTOM,
                                         /*can_activate=*/true);
   CHECK(controller_);
@@ -33,18 +138,92 @@ void ViewsOverlayBrowser::Initialize(
 
 void ViewsOverlayBrowser::Destroy() {
   window_ = nullptr;
-  controller_->Destroy();
-  controller_ = nullptr;
 
+  if (popout_window_) {
+    // The BrowserView is popped out, and the main Window is closed first.
+    // Let the popout Window handle BrowserView destruction.
+    PopoutWindowDelegate::GetForWindow(popout_window_)->OverlayDestroyed();
+    popout_window_->Close();
+    popout_window_ = nullptr;
+  }
+
+  if (controller_) {
+    if (controller_->IsValid()) {
+      controller_->Destroy();
+    }
+    controller_ = nullptr;
+    owner_window_->UpdateDraggableRegions();
+  }
+
+  if (browser_view_) {
     // We hold the last reference to the BrowserView, and releasing it will
-  // trigger overlay Browser destruction. OnBeforeClose for that Browser may be
-  // called synchronously or asynchronously depending on whether beforeunload
-  // needs to be dispatched.
+    // trigger overlay Browser destruction. OnBeforeClose for that Browser may
+    // be called synchronously or asynchronously depending on whether
+    // beforeunload needs to be dispatched.
     DCHECK(browser_view_->HasOneRef());
     browser_view_ = nullptr;
   }
+}
+
+bool ViewsOverlayBrowser::IsValid() const {
+  // Intentionally not checking |popout_window_->IsValid()| here because the
+  // pop-in behavior will be triggered by |popout_window_| closing.
+  return (controller_ && controller_->IsValid()) || popout_window_;
+}
+
+void ViewsOverlayBrowser::ToggleBrowserView() {
+  if (browser_view_) {
+    PopOutBrowserView();
+  } else {
+    PopInBrowserView();
+  }
+
+  owner_window_->UpdateDraggableRegions();
+}
+
+void ViewsOverlayBrowser::PopOutBrowserView() {
+  CHECK(browser_view_);
+
+  DCHECK(controller_ && controller_->IsValid());
+  controller_->Destroy();
+  controller_ = nullptr;
+
+  // We hold the only reference to the BrowserView.
+  DCHECK(browser_view_->HasOneRef());
+
+  // Create a new popout Window and pass ownership of the BrowserView.
+  CHECK(!popout_window_);
+  popout_window_ = CefWindow::CreateTopLevelWindow(
+      new PopoutWindowDelegate(weak_ptr_factory_.GetWeakPtr(), browser_view_));
+  browser_view_ = nullptr;
+}
+
+void ViewsOverlayBrowser::PopInBrowserView() {
+  CHECK(!browser_view_);
+
+  // Resume ownership of the BrowserView and close the popout Window.
+  CHECK(popout_window_);
+  browser_view_ =
+      PopoutWindowDelegate::GetForWindow(popout_window_)->DetachBrowserView();
+  popout_window_->RemoveChildView(browser_view_);
+  popout_window_->Close();
+  popout_window_ = nullptr;
+
+  // We hold the only reference to the BrowserView.
+  DCHECK(browser_view_->HasOneRef());
+
+  // Add the BrowserView to an overlay in the main window.
+  controller_ = window_->AddOverlayView(browser_view_, CEF_DOCKING_MODE_CUSTOM,
+                                        /*can_activate=*/true);
+  CHECK(controller_);
+
+  // Make sure the overlay is positioned correctly.
+  UpdateBounds(last_insets_);
+}
 
 void ViewsOverlayBrowser::UpdateBounds(CefInsets insets) {
+  last_insets_ = insets;
+
   if (!controller_) {
     return;
   }
@@ -78,10 +257,38 @@ void ViewsOverlayBrowser::UpdateDraggableRegions(
   }
 }
 
+bool ViewsOverlayBrowser::OnAccelerator(CefRefPtr<CefWindow> window,
+                                        int command_id) {
+  if (IsValid() && command_id == ID_POPOUT_OVERLAY) {
+    ToggleBrowserView();
+    return true;
+  }
+  return false;
+}
+
+void ViewsOverlayBrowser::PopOutWindowDestroyed() {
+  popout_window_ = nullptr;
+}
+
 CefSize ViewsOverlayBrowser::GetMinimumSize(CefRefPtr<CefView> view) {
   return CefSize(200, 200);
 }
 
+void ViewsOverlayBrowser::OnBrowserDestroyed(
+    CefRefPtr<CefBrowserView> browser_view,
+    CefRefPtr<CefBrowser> browser) {
+  // Might be popped out currently.
+  if (!controller_) {
+    return;
+  }
+
+  // Destroy the overlay controller if the browser is destroyed first (e.g. via
+  // `window.close()`).
+  controller_->Destroy();
+  controller_ = nullptr;
+  owner_window_->UpdateDraggableRegions();
+}
+
 CefRefPtr<CefBrowserViewDelegate>
 ViewsOverlayBrowser::GetDelegateForPopupBrowserView(
     CefRefPtr<CefBrowserView> browser_view,

tests/cefclient/browser/views_overlay_browser.h

@@ -6,6 +6,7 @@
 #define CEF_TESTS_CEFCLIENT_BROWSER_VIEWS_OVERLAY_BROWSER_H_
 #pragma once
 
+#include "include/base/cef_weak_ptr.h"
 #include "include/views/cef_browser_view.h"
 #include "include/views/cef_browser_view_delegate.h"
 #include "include/views/cef_overlay_controller.h"
@@ -28,17 +29,28 @@ class ViewsOverlayBrowser : public CefBrowserViewDelegate {
                   CefRefPtr<CefRequestContext> request_context);
   void Destroy();
 
+  bool IsValid() const;
+
+  // Move the overlay BrowserView to/from a popout Window.
+  void ToggleBrowserView();
+
   // Update browser bounds.
   void UpdateBounds(CefInsets insets);
 
   // Exclude all regions obscured by overlays.
   void UpdateDraggableRegions(std::vector<CefDraggableRegion>& window_regions);
 
+  bool OnAccelerator(CefRefPtr<CefWindow> window, int command_id);
+
+  void PopOutWindowDestroyed();
+
  private:
   // CefViewDelegate methods:
   CefSize GetMinimumSize(CefRefPtr<CefView> view) override;
 
   // CefBrowserViewDelegate methods:
+  void OnBrowserDestroyed(CefRefPtr<CefBrowserView> browser_view,
+                          CefRefPtr<CefBrowser> browser) override;
   CefRefPtr<CefBrowserViewDelegate> GetDelegateForPopupBrowserView(
       CefRefPtr<CefBrowserView> browser_view,
       const CefBrowserSettings& settings,
@@ -49,10 +61,21 @@ class ViewsOverlayBrowser : public CefBrowserViewDelegate {
                                  bool is_devtools) override;
   cef_runtime_style_t GetBrowserRuntimeStyle() override;
 
+  // Move the BrowserView to a new top-level Window.
+  void PopOutBrowserView();
+
+  // Return the BrowserView to the overlay.
+  void PopInBrowserView();
+
   ViewsWindow* const owner_window_;
   CefRefPtr<CefWindow> window_;
   CefRefPtr<CefBrowserView> browser_view_;
   CefRefPtr<CefOverlayController> controller_;
+  CefInsets last_insets_;
+
+  CefRefPtr<CefWindow> popout_window_;
+
+  base::WeakPtrFactory<ViewsOverlayBrowser> weak_ptr_factory_{this};
 
   IMPLEMENT_REFCOUNTING(ViewsOverlayBrowser);
   DISALLOW_COPY_AND_ASSIGN(ViewsOverlayBrowser);

tests/cefclient/browser/views_window.cc

@@ -354,6 +354,8 @@ void ViewsWindow::SetDraggableRegions(
     return;
   }
 
+  last_regions_ = regions;
+
   // Convert the regions from BrowserView to Window coordinates.
   std::vector<CefDraggableRegion> window_regions = regions;
   for (auto& region : window_regions) {
@@ -448,6 +450,10 @@ void ViewsWindow::SetTitlebarHeight(const std::optional<float>& height) {
   NudgeWindow();
 }
 
+void ViewsWindow::UpdateDraggableRegions() {
+  SetDraggableRegions(last_regions_);
+}
+
 CefRefPtr<CefBrowserViewDelegate> ViewsWindow::GetDelegateForPopupBrowserView(
     CefRefPtr<CefBrowserView> browser_view,
     const CefBrowserSettings& settings,
@@ -914,6 +920,8 @@ bool ViewsWindow::OnAccelerator(CefRefPtr<CefWindow> window, int command_id) {
   if (command_id == ID_QUIT) {
     delegate_->OnExit();
     return true;
+  } else if (overlay_browser_) {
+    return overlay_browser_->OnAccelerator(window, command_id);
   }
 
   return false;

tests/cefclient/browser/views_window.h

@@ -129,6 +129,8 @@ class ViewsWindow : public CefBrowserViewDelegate,
                                    std::optional<CefRect>& dip_bounds);
   void SetTitlebarHeight(const std::optional<float>& height);
 
+  void UpdateDraggableRegions();
+
   // CefBrowserViewDelegate methods:
   CefRefPtr<CefBrowserViewDelegate> GetDelegateForPopupBrowserView(
       CefRefPtr<CefBrowserView> browser_view,
@@ -252,7 +254,7 @@ class ViewsWindow : public CefBrowserViewDelegate,
   void NudgeWindow();
 
   const WindowType type_;
-  Delegate* delegate_;  // Not owned by this object.
+  Delegate* const delegate_;  // Not owned by this object.
   const bool use_alloy_style_;
   bool use_alloy_style_window_;
   CefRefPtr<CefBrowserView> browser_view_;
@@ -301,6 +303,8 @@ class ViewsWindow : public CefBrowserViewDelegate,
   bool can_go_back_ = false;
   bool can_go_forward_ = false;
 
+  std::vector<CefDraggableRegion> last_regions_;
+
   IMPLEMENT_REFCOUNTING(ViewsWindow);
   DISALLOW_COPY_AND_ASSIGN(ViewsWindow);
 };