diff --git chrome/browser/ui/browser_command_controller.cc chrome/browser/ui/browser_command_controller.cc
index c1f28ebc372df..275657f54c517 100644
--- chrome/browser/ui/browser_command_controller.cc
+++ chrome/browser/ui/browser_command_controller.cc
@@ -395,6 +395,7 @@ bool BrowserCommandController::ExecuteCommandWithDisposition(
   // choose to not implement CommandUpdaterDelegate inside this class and
   // therefore command_updater_ doesn't have the delegate set).
   if (!SupportsCommand(id) || !IsCommandEnabled(id)) {
+    LOG(WARNING) << "Invalid/disabled command " << id;
     return false;
   }
 
@@ -411,6 +412,13 @@ bool BrowserCommandController::ExecuteCommandWithDisposition(
   DCHECK(command_updater_.IsCommandEnabled(id))
       << "Invalid/disabled command " << id;
 
+#if BUILDFLAG(ENABLE_CEF)
+  if (browser_->cef_delegate() &&
+      browser_->cef_delegate()->HandleCommand(id, disposition)) {
+    return true;
+  }
+#endif
+
   // The order of commands in this switch statement must match the function
   // declaration order in browser.h!
   switch (id) {
@@ -1102,11 +1110,13 @@ void BrowserCommandController::TabRestoreServiceLoaded(
 // BrowserCommandController, private:
 
 bool BrowserCommandController::IsShowingMainUI() {
-  return browser_->SupportsWindowFeature(Browser::FEATURE_TABSTRIP);
+  return browser_->SupportsWindowFeature(Browser::FEATURE_TABSTRIP) ||
+         browser_->toolbar_overridden();
 }
 
 bool BrowserCommandController::IsShowingLocationBar() {
-  return browser_->SupportsWindowFeature(Browser::FEATURE_LOCATIONBAR);
+  return browser_->SupportsWindowFeature(Browser::FEATURE_LOCATIONBAR) ||
+         browser_->toolbar_overridden();
 }
 
 bool BrowserCommandController::IsWebAppOrCustomTab() const {
diff --git chrome/browser/ui/toolbar/app_menu_model.cc chrome/browser/ui/toolbar/app_menu_model.cc
index f6c50fc75faf8..30b0f9fa68554 100644
--- chrome/browser/ui/toolbar/app_menu_model.cc
+++ chrome/browser/ui/toolbar/app_menu_model.cc
@@ -192,6 +192,57 @@ void SetCommandIcon(ui::SimpleMenuModel* model,
   }
 }
 
+#if BUILDFLAG(ENABLE_CEF)
+using IsVisibleCallback = base::RepeatingCallback<bool(int)>;
+
+void FilterMenuModel(ui::SimpleMenuModel* model,
+                     const IsVisibleCallback& is_visible) {
+  absl::optional<size_t> last_separator;
+  size_t visible_ct = 0;
+  for (size_t i = 0; i < model->GetItemCount(); ++i) {
+    const auto type = model->GetTypeAt(i);
+    if (type == ui::MenuModel::TYPE_SEPARATOR) {
+      if (last_separator) {
+        // Remove multiple separators in a row. Prefer to remove a NORMAL
+        // separator if possible (as compared to zoom/edit controls which use
+        // UPPER/LOWER separators).
+        if (model->GetSeparatorTypeAt(*last_separator) ==
+            ui::NORMAL_SEPARATOR) {
+          model->RemoveItemAt(*last_separator);
+          i--;
+          last_separator = i;
+        } else {
+          model->RemoveItemAt(i);
+          i--;
+        }
+      } else if (visible_ct == 0) {
+        // Remove leading separator.
+        model->RemoveItemAt(i);
+        i--;
+      } else {
+        last_separator = i;
+      }
+      visible_ct = 0;
+    } else if (is_visible.Run(model->GetCommandIdAt(i))) {
+      last_separator = absl::nullopt;
+      visible_ct++;
+
+      if (type == ui::MenuModel::TYPE_SUBMENU) {
+        // Filter sub-menu.
+        auto sub_model =
+            static_cast<ui::SimpleMenuModel*>(model->GetSubmenuModelAt(i));
+        FilterMenuModel(sub_model, is_visible);
+      }
+    }
+  }
+
+  if (last_separator) {
+    // Remove trailing separator.
+    model->RemoveItemAt(*last_separator);
+  }
+}
+#endif  // BUILDFLAG(ENABLE_CEF)
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -960,7 +1011,7 @@ bool AppMenuModel::IsCommandIdChecked(int command_id) const {
   return false;
 }
 
-bool AppMenuModel::IsCommandIdEnabled(int command_id) const {
+bool AppMenuModel::IsCommandIdEnabledInternal(int command_id) const {
   GlobalError* error =
       GlobalErrorServiceFactory::GetForProfile(browser_->profile())
           ->GetGlobalErrorByMenuItemCommandID(command_id);
@@ -975,7 +1026,7 @@ bool AppMenuModel::IsCommandIdEnabled(int command_id) const {
   }
 }
 
-bool AppMenuModel::IsCommandIdVisible(int command_id) const {
+bool AppMenuModel::IsCommandIdVisibleInternal(int command_id) const {
   switch (command_id) {
     case IDC_PIN_TO_START_SCREEN:
       return false;
@@ -998,6 +1049,34 @@ bool AppMenuModel::IsCommandIdVisible(int command_id) const {
   }
 }
 
+bool AppMenuModel::IsCommandIdEnabled(int command_id) const {
+  if (!IsCommandIdEnabledInternal(command_id)) {
+    return false;
+  }
+
+#if BUILDFLAG(ENABLE_CEF)
+  if (browser_->cef_delegate()) {
+    return browser_->cef_delegate()->IsAppMenuItemEnabled(command_id);
+  }
+#endif
+
+  return true;
+}
+
+bool AppMenuModel::IsCommandIdVisible(int command_id) const {
+  if (!IsCommandIdVisibleInternal(command_id)) {
+    return false;
+  }
+
+#if BUILDFLAG(ENABLE_CEF)
+  if (browser_->cef_delegate()) {
+    return browser_->cef_delegate()->IsAppMenuItemVisible(command_id);
+  }
+#endif
+
+  return true;
+}
+
 bool AppMenuModel::IsCommandIdAlerted(int command_id) const {
   if ((command_id == IDC_RECENT_TABS_MENU) ||
       (command_id == AppMenuModel::kMinRecentTabsCommandId)) {
@@ -1148,11 +1227,15 @@ void AppMenuModel::Build() {
     }
   }
 
-  AddSeparator(features::IsChromeRefresh2023() ? ui::NORMAL_SEPARATOR
-                                               : ui::LOWER_SEPARATOR);
-  CreateZoomMenu();
-  AddSeparator(features::IsChromeRefresh2023() ? ui::NORMAL_SEPARATOR
-                                               : ui::UPPER_SEPARATOR);
+  if (IsCommandIdVisible(IDC_ZOOM_MENU)) {
+    AddSeparator(features::IsChromeRefresh2023() ? ui::NORMAL_SEPARATOR
+                                                 : ui::LOWER_SEPARATOR);
+    CreateZoomMenu();
+    AddSeparator(features::IsChromeRefresh2023() ? ui::NORMAL_SEPARATOR
+                                                 : ui::UPPER_SEPARATOR);
+  } else {
+    AddSeparator(ui::NORMAL_SEPARATOR);
+  }
 
   AddItemWithStringId(IDC_PRINT, IDS_PRINT);
 
@@ -1243,9 +1326,13 @@ void AppMenuModel::Build() {
                          kMoreToolsMenuItem);
 
   if (!features::IsChromeRefresh2023()) {
-    AddSeparator(ui::LOWER_SEPARATOR);
-    CreateCutCopyPasteMenu();
-    AddSeparator(ui::UPPER_SEPARATOR);
+    if (IsCommandIdVisible(IDC_EDIT_MENU)) {
+      AddSeparator(ui::LOWER_SEPARATOR);
+      CreateCutCopyPasteMenu();
+      AddSeparator(ui::UPPER_SEPARATOR);
+    } else {
+      AddSeparator(ui::NORMAL_SEPARATOR);
+    }
   }
 
   if (!features::IsChromeRefresh2023()) {
@@ -1327,6 +1414,11 @@ void AppMenuModel::Build() {
     SetCommandIcon(this, IDC_EXIT, kExitMenuIcon);
   }
 
+#if BUILDFLAG(ENABLE_CEF)
+  FilterMenuModel(this, base::BindRepeating(&AppMenuModel::IsCommandIdVisible,
+                                            base::Unretained(this)));
+#endif
+
   uma_action_recorded_ = false;
 }
 
diff --git chrome/browser/ui/toolbar/app_menu_model.h chrome/browser/ui/toolbar/app_menu_model.h
index 8648fccbe4a2e..386dee69b5eff 100644
--- chrome/browser/ui/toolbar/app_menu_model.h
+++ chrome/browser/ui/toolbar/app_menu_model.h
@@ -258,6 +258,9 @@ class AppMenuModel : public ui::SimpleMenuModel,
   // Appends a zoom menu (without separators).
   void CreateZoomMenu();
 
+  bool IsCommandIdEnabledInternal(int command_id) const;
+  bool IsCommandIdVisibleInternal(int command_id) const;
+
  private:
   // Adds actionable global error menu items to the menu.
   // Examples: Extension permissions and sign in errors.
diff --git chrome/browser/ui/views/find_bar_host.cc chrome/browser/ui/views/find_bar_host.cc
index 59024587ef6b7..0c30aa71768cf 100644
--- chrome/browser/ui/views/find_bar_host.cc
+++ chrome/browser/ui/views/find_bar_host.cc
@@ -412,6 +412,12 @@ void FindBarHost::GetWidgetBounds(gfx::Rect* bounds) {
   // The BrowserView does Layout for the components that we care about
   // positioning relative to, so we ask it to tell us where we should go.
   *bounds = browser_view()->GetFindBarBoundingBox();
+
+#if BUILDFLAG(ENABLE_CEF)
+  if (browser_view()->browser() && browser_view()->browser()->cef_delegate()) {
+    browser_view()->browser()->cef_delegate()->UpdateFindBarBoundingBox(bounds);
+  }
+#endif
 }
 
 void FindBarHost::RegisterAccelerators() {
diff --git chrome/browser/ui/views/frame/browser_frame.cc chrome/browser/ui/views/frame/browser_frame.cc
index 24b85357b90b8..67e1bacb8d518 100644
--- chrome/browser/ui/views/frame/browser_frame.cc
+++ chrome/browser/ui/views/frame/browser_frame.cc
@@ -75,15 +75,23 @@ bool IsUsingLinuxSystemTheme(Profile* profile) {
 ////////////////////////////////////////////////////////////////////////////////
 // BrowserFrame, public:
 
+BrowserFrame::BrowserFrame() : BrowserFrame(nullptr) {}
+
 BrowserFrame::BrowserFrame(BrowserView* browser_view)
     : native_browser_frame_(nullptr),
       root_view_(nullptr),
       browser_frame_view_(nullptr),
-      browser_view_(browser_view) {
-  browser_view_->set_frame(this);
+      browser_view_(nullptr) {
   set_is_secondary_widget(false);
   // Don't focus anything on creation, selecting a tab will set the focus.
   set_focus_on_creation(false);
+  if (browser_view)
+    InitBrowserView(browser_view);
+}
+
+void BrowserFrame::InitBrowserView(BrowserView* browser_view) {
+  browser_view_ = browser_view;
+  browser_view_->set_frame(this);
 }
 
 BrowserFrame::~BrowserFrame() {}
@@ -178,6 +186,12 @@ void BrowserFrame::LayoutWebAppWindowTitle(
 }
 
 int BrowserFrame::GetTopInset() const {
+  if (!browser_frame_view_) {
+    // With CEF the browser may already be part of a larger Views layout. Zero
+    // out the adjustment in BrowserView::GetTopInsetInBrowserView() so that
+    // the browser isn't shifted to the top of the window.
+    return browser_view_->y();
+  }
   return browser_frame_view_->GetTopInset(false);
 }
 
@@ -194,6 +208,8 @@ BrowserNonClientFrameView* BrowserFrame::GetFrameView() const {
 }
 
 bool BrowserFrame::UseCustomFrame() const {
+  if (!native_browser_frame_)
+    return true;
   return native_browser_frame_->UseCustomFrame();
 }
 
@@ -207,20 +223,30 @@ bool BrowserFrame::ShouldDrawFrameHeader() const {
 
 void BrowserFrame::GetWindowPlacement(gfx::Rect* bounds,
                                       ui::WindowShowState* show_state) const {
+  if (!native_browser_frame_) {
+    *show_state = ui::SHOW_STATE_DEFAULT;
+    return;
+  }
   return native_browser_frame_->GetWindowPlacement(bounds, show_state);
 }
 
 content::KeyboardEventProcessingResult BrowserFrame::PreHandleKeyboardEvent(
     const content::NativeWebKeyboardEvent& event) {
+  if (!native_browser_frame_)
+    return content::KeyboardEventProcessingResult::NOT_HANDLED;
   return native_browser_frame_->PreHandleKeyboardEvent(event);
 }
 
 bool BrowserFrame::HandleKeyboardEvent(
     const content::NativeWebKeyboardEvent& event) {
+  if (!native_browser_frame_)
+    return false;
   return native_browser_frame_->HandleKeyboardEvent(event);
 }
 
 void BrowserFrame::OnBrowserViewInitViewsComplete() {
+  if (!browser_frame_view_)
+    return;
   browser_frame_view_->OnBrowserViewInitViewsComplete();
 }
 
@@ -300,6 +326,8 @@ BrowserFrame::GetCustomTheme() const {
 }
 
 void BrowserFrame::OnNativeWidgetWorkspaceChanged() {
+  if (!browser_view_)
+    return;
   chrome::SaveWindowWorkspace(browser_view_->browser(), GetWorkspace());
   chrome::SaveWindowVisibleOnAllWorkspaces(browser_view_->browser(),
                                            IsVisibleOnAllWorkspaces());
@@ -411,6 +439,8 @@ void BrowserFrame::OnNativeThemeUpdated(ui::NativeTheme* observed_theme) {
 
 ui::ColorProviderManager::Key BrowserFrame::GetColorProviderKey() const {
   auto key = Widget::GetColorProviderKey();
+  if (!browser_view_)
+    return key;
   key.frame_type = UseCustomFrame()
                        ? ui::ColorProviderManager::FrameType::kChromium
                        : ui::ColorProviderManager::FrameType::kNative;
@@ -420,6 +450,9 @@ ui::ColorProviderManager::Key BrowserFrame::GetColorProviderKey() const {
 }
 
 absl::optional<SkColor> BrowserFrame::GetUserColor() const {
+  if (!browser_view_) {
+    return absl::nullopt;
+  }
 #if BUILDFLAG(IS_CHROMEOS_ASH)
   // ChromeOS SystemWebApps use the OS theme all the time.
   if (ash::IsSystemWebApp(browser_view_->browser())) {
@@ -533,5 +566,8 @@ bool BrowserFrame::RegenerateFrameOnThemeChange(
 }
 
 bool BrowserFrame::IsIncognitoBrowser() const {
+  if (!browser_view_) {
+    return true;
+  }
   return browser_view_->browser()->profile()->IsIncognitoProfile();
 }
diff --git chrome/browser/ui/views/frame/browser_frame.h chrome/browser/ui/views/frame/browser_frame.h
index 795f057fedc51..54b08509919af 100644
--- chrome/browser/ui/views/frame/browser_frame.h
+++ chrome/browser/ui/views/frame/browser_frame.h
@@ -61,7 +61,9 @@ enum class TabDragKind {
 // This is a virtual interface that allows system specific browser frames.
 class BrowserFrame : public views::Widget, public views::ContextMenuController {
  public:
+  BrowserFrame();
   explicit BrowserFrame(BrowserView* browser_view);
+  void InitBrowserView(BrowserView* browser_view);
 
   BrowserFrame(const BrowserFrame&) = delete;
   BrowserFrame& operator=(const BrowserFrame&) = delete;
diff --git chrome/browser/ui/views/frame/browser_view.cc chrome/browser/ui/views/frame/browser_view.cc
index 39a1660cae03a..0faf50eb14298 100644
--- chrome/browser/ui/views/frame/browser_view.cc
+++ chrome/browser/ui/views/frame/browser_view.cc
@@ -314,11 +314,10 @@ using content::NativeWebKeyboardEvent;
 using content::WebContents;
 using web_modal::WebContentsModalDialogHost;
 
-namespace {
+// static
+const char BrowserView::kBrowserViewKey[] = "__BROWSER_VIEW__";
 
-// The name of a key to store on the window handle so that other code can
-// locate this object using just the handle.
-const char* const kBrowserViewKey = "__BROWSER_VIEW__";
+namespace {
 
 #if BUILDFLAG(IS_CHROMEOS_ASH)
 // UMA histograms that record animation smoothness for tab loading animation.
@@ -789,11 +788,22 @@ class BrowserView::AccessibilityModeObserver : public ui::AXModeObserver {
 ///////////////////////////////////////////////////////////////////////////////
 // BrowserView, public:
 
+BrowserView::BrowserView() : BrowserView(nullptr) {}
+
 BrowserView::BrowserView(std::unique_ptr<Browser> browser)
     : views::ClientView(nullptr, nullptr),
-      browser_(std::move(browser)),
       accessibility_mode_observer_(
           std::make_unique<AccessibilityModeObserver>(this)) {
+  if (browser)
+    InitBrowser(std::move(browser));
+}
+
+void BrowserView::InitBrowser(std::unique_ptr<Browser> browser) {
+  DCHECK(!browser_);
+  browser_ = std::move(browser);
+
+  immersive_mode_controller_ = chrome::CreateImmersiveModeController(this);
+
   SetShowIcon(
       ::ShouldShowWindowIcon(browser_.get(), AppUsesWindowControlsOverlay()));
 
@@ -837,7 +847,6 @@ BrowserView::BrowserView(std::unique_ptr<Browser> browser)
   }
 
   browser_->tab_strip_model()->AddObserver(this);
-  immersive_mode_controller_ = chrome::CreateImmersiveModeController(this);
 
   // Top container holds tab strip region and toolbar and lives at the front of
   // the view hierarchy.
@@ -893,8 +902,15 @@ BrowserView::BrowserView(std::unique_ptr<Browser> browser)
   contents_container->SetLayoutManager(std::make_unique<ContentsLayoutManager>(
       devtools_web_view_, contents_web_view_));
 
-  toolbar_ = top_container_->AddChildView(
-      std::make_unique<ToolbarView>(browser_.get(), this));
+  toolbar_ = OverrideCreateToolbar(browser_.get(), this);
+  if (!toolbar_) {
+    toolbar_ = new ToolbarView(browser_.get(), this, absl::nullopt);
+  } else {
+    browser_->set_toolbar_overridden(true);
+    // Update state that depends on the above flag.
+    browser_->command_controller()->FullscreenStateChanged();
+  }
+  top_container_->AddChildView(base::WrapUnique(toolbar_.get()));
 
   contents_separator_ =
       top_container_->AddChildView(std::make_unique<ContentsSeparator>());
@@ -1087,12 +1103,14 @@ gfx::Size BrowserView::GetWebAppFrameToolbarPreferredSize() const {
 
 #if BUILDFLAG(IS_MAC)
 bool BrowserView::UsesImmersiveFullscreenMode() const {
+  if (!base::FeatureList::IsEnabled(features::kImmersiveFullscreen)) {
+    return false;
+  }
   const bool is_pwa =
       base::FeatureList::IsEnabled(features::kImmersiveFullscreenPWAs) &&
       GetIsWebAppType();
   const bool is_tabbed_window = GetSupportsTabStrip();
-  return base::FeatureList::IsEnabled(features::kImmersiveFullscreen) &&
-         (is_pwa || is_tabbed_window);
+  return is_pwa || is_tabbed_window;
 }
 
 bool BrowserView::UsesImmersiveFullscreenTabbedMode() const {
@@ -1817,6 +1835,8 @@ bool BrowserView::ShouldHideUIForFullscreen() const {
   if (immersive_mode_controller_->IsEnabled())
     return false;
 
+  if (!frame_->GetFrameView())
+    return false;
   return frame_->GetFrameView()->ShouldHideTopUIForFullscreen();
 }
 
@@ -2722,7 +2742,8 @@ DownloadShelf* BrowserView::GetDownloadShelf() {
 }
 
 DownloadBubbleUIController* BrowserView::GetDownloadBubbleUIController() {
-  DCHECK(toolbar_button_provider_);
+  if (!toolbar_button_provider_)
+    return nullptr;
   if (auto* download_button = toolbar_button_provider_->GetDownloadButton())
     return download_button->bubble_controller();
   return nullptr;
@@ -3222,7 +3243,8 @@ void BrowserView::ReparentTopContainerForEndOfImmersive() {
   if (top_container()->parent() == this)
     return;
 
-  overlay_view_->SetVisible(false);
+  if (overlay_view_)
+    overlay_view_->SetVisible(false);
   top_container()->DestroyLayer();
   AddChildViewAt(top_container(), 0);
   EnsureFocusOrder();
@@ -3776,8 +3798,10 @@ void BrowserView::Layout() {
 
   // TODO(jamescook): Why was this in the middle of layout code?
   toolbar_->location_bar()->omnibox_view()->SetFocusBehavior(
-      IsToolbarVisible() ? FocusBehavior::ALWAYS : FocusBehavior::NEVER);
-  frame()->GetFrameView()->UpdateMinimumSize();
+      (IsToolbarVisible() || browser_->toolbar_overridden()) ?
+          FocusBehavior::ALWAYS : FocusBehavior::NEVER);
+  if (frame()->GetFrameView())
+    frame()->GetFrameView()->UpdateMinimumSize();
 
   // Some of the situations when the BrowserView is laid out are:
   // - Enter/exit immersive fullscreen mode.
@@ -3843,6 +3867,11 @@ void BrowserView::AddedToWidget() {
   SetThemeProfileForWindow(GetNativeWindow(), browser_->profile());
 #endif
 
+  // This browser view may already have a custom button provider set (e.g the
+  // hosted app frame).
+  if (!toolbar_button_provider_)
+    SetToolbarButtonProvider(toolbar_);
+
   toolbar_->Init();
 
   // TODO(pbos): Investigate whether the side panels should be creatable when
@@ -3889,13 +3918,9 @@ void BrowserView::AddedToWidget() {
 
   EnsureFocusOrder();
 
-  // This browser view may already have a custom button provider set (e.g the
-  // hosted app frame).
-  if (!toolbar_button_provider_)
-    SetToolbarButtonProvider(toolbar_);
-
   frame_->OnBrowserViewInitViewsComplete();
-  frame_->GetFrameView()->UpdateMinimumSize();
+  if (frame_->GetFrameView())
+    frame_->GetFrameView()->UpdateMinimumSize();
   using_native_frame_ = frame_->ShouldUseNativeFrame();
 
   MaybeInitializeWebUITabStrip();
@@ -4300,7 +4325,8 @@ void BrowserView::ProcessFullscreen(bool fullscreen,
   // Undo our anti-jankiness hacks and force a re-layout.
   in_process_fullscreen_ = false;
   ToolbarSizeChanged(false);
-  frame_->GetFrameView()->OnFullscreenStateChanged();
+  if (frame_->GetFrameView())
+    frame_->GetFrameView()->OnFullscreenStateChanged();
 }
 
 bool BrowserView::ShouldUseImmersiveFullscreenForUrl(const GURL& url) const {
@@ -4671,6 +4697,8 @@ Profile* BrowserView::GetProfile() {
 }
 
 void BrowserView::UpdateUIForTabFullscreen() {
+  if (!frame_->GetFrameView())
+    return;
   frame()->GetFrameView()->UpdateFullscreenTopUI();
 }
 
@@ -4693,6 +4721,8 @@ void BrowserView::HideDownloadShelf() {
 }
 
 bool BrowserView::CanUserExitFullscreen() const {
+  if (!frame_->GetFrameView())
+    return true;
   return frame_->GetFrameView()->CanUserExitFullscreen();
 }
 
diff --git chrome/browser/ui/views/frame/browser_view.h chrome/browser/ui/views/frame/browser_view.h
index 3e812382f77e6..d821b03bfa510 100644
--- chrome/browser/ui/views/frame/browser_view.h
+++ chrome/browser/ui/views/frame/browser_view.h
@@ -124,11 +124,16 @@ class BrowserView : public BrowserWindow,
                     public webapps::AppBannerManager::Observer {
  public:
   METADATA_HEADER(BrowserView);
+  BrowserView();
   explicit BrowserView(std::unique_ptr<Browser> browser);
+  void InitBrowser(std::unique_ptr<Browser> browser);
   BrowserView(const BrowserView&) = delete;
   BrowserView& operator=(const BrowserView&) = delete;
   ~BrowserView() override;
 
+  // Key used to bind BrowserView to the Widget with which it is associated.
+  static const char kBrowserViewKey[];
+
   void set_frame(BrowserFrame* frame) {
     frame_ = frame;
     paint_as_active_subscription_ =
@@ -783,6 +788,12 @@ class BrowserView : public BrowserWindow,
     return web_app_frame_toolbar();
   }
 
+ protected:
+  virtual ToolbarView* OverrideCreateToolbar(Browser* browser,
+                                             BrowserView* browser_view) {
+    return nullptr;
+  }
+
  private:
   // Do not friend BrowserViewLayout. Use the BrowserViewLayoutDelegate
   // interface to keep these two classes decoupled and testable.
diff --git chrome/browser/ui/views/frame/browser_view_layout.cc chrome/browser/ui/views/frame/browser_view_layout.cc
index cf12bbd30e086..a227f64d8d5e9 100644
--- chrome/browser/ui/views/frame/browser_view_layout.cc
+++ chrome/browser/ui/views/frame/browser_view_layout.cc
@@ -47,6 +47,10 @@
 #include "ui/views/window/client_view.h"
 #include "ui/views/window/hit_test_utils.h"
 
+#if BUILDFLAG(ENABLE_CEF)
+#include "cef/libcef/browser/chrome/views/chrome_views_util.h"
+#endif
+
 using views::View;
 using web_modal::ModalDialogHostObserver;
 using web_modal::WebContentsModalDialogHost;
@@ -560,6 +564,13 @@ int BrowserViewLayout::LayoutWebUITabStrip(int top) {
 
 int BrowserViewLayout::LayoutToolbar(int top) {
   TRACE_EVENT0("ui", "BrowserViewLayout::LayoutToolbar");
+#if BUILDFLAG(ENABLE_CEF)
+  if (cef::IsCefView(toolbar_)) {
+    // CEF may take ownership of the toolbar. Early exit to avoid the DCHECK
+    // in LayoutManager::SetViewVisibility().
+    return top;
+  }
+#endif
   int browser_view_width = vertical_layout_rect_.width();
   bool toolbar_visible = delegate_->IsToolbarVisible();
   int height = toolbar_visible ? toolbar_->GetPreferredSize().height() : 0;
diff --git chrome/browser/ui/views/frame/contents_web_view.cc chrome/browser/ui/views/frame/contents_web_view.cc
index 5e059b9878fc2..c1f6fbcd40ec4 100644
--- chrome/browser/ui/views/frame/contents_web_view.cc
+++ chrome/browser/ui/views/frame/contents_web_view.cc
@@ -26,6 +26,11 @@
 ContentsWebView::ContentsWebView(content::BrowserContext* browser_context)
     : views::WebView(browser_context),
       status_bubble_(nullptr) {
+  // Mouse events on draggable regions will not be handled by the WebView.
+  // Avoid the resulting DCHECK in NativeViewHost::OnMousePressed by
+  // configuring the NativeViewHost not to process events via the view
+  // hierarchy.
+  holder()->SetCanProcessEventsWithinSubtree(false);
 }
 
 ContentsWebView::~ContentsWebView() {
diff --git chrome/browser/ui/views/page_action/page_action_icon_controller.cc chrome/browser/ui/views/page_action/page_action_icon_controller.cc
index 85a3c9eec15fe..e9a8bc50532f8 100644
--- chrome/browser/ui/views/page_action/page_action_icon_controller.cc
+++ chrome/browser/ui/views/page_action/page_action_icon_controller.cc
@@ -93,6 +93,12 @@ void PageActionIconController::Init(const PageActionIconParams& params,
   };
 
   for (PageActionIconType type : params.types_enabled) {
+#if BUILDFLAG(ENABLE_CEF)
+    if (params.browser && params.browser->cef_delegate() &&
+        !params.browser->cef_delegate()->IsPageActionIconVisible(type)) {
+      continue;
+    }
+#endif
     switch (type) {
       case PageActionIconType::kPaymentsOfferNotification:
         add_page_action_icon(
diff --git chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc
index 2753a95f8ff35..9745477102917 100644
--- chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc
+++ chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc
@@ -559,33 +559,47 @@ gfx::Range BrowserTabStripController::ListTabsInGroup(
 }
 
 bool BrowserTabStripController::IsFrameCondensed() const {
+  if (!GetFrameView())
+    return false;
   return GetFrameView()->IsFrameCondensed();
 }
 
 bool BrowserTabStripController::HasVisibleBackgroundTabShapes() const {
+  if (!GetFrameView())
+    return false;
   return GetFrameView()->HasVisibleBackgroundTabShapes(
       BrowserFrameActiveState::kUseCurrent);
 }
 
 bool BrowserTabStripController::EverHasVisibleBackgroundTabShapes() const {
+  if (!GetFrameView())
+    return false;
   return GetFrameView()->EverHasVisibleBackgroundTabShapes();
 }
 
 bool BrowserTabStripController::ShouldPaintAsActiveFrame() const {
+  if (!GetFrameView())
+    return false;
   return GetFrameView()->ShouldPaintAsActive();
 }
 
 bool BrowserTabStripController::CanDrawStrokes() const {
+  if (!GetFrameView())
+    return false;
   return GetFrameView()->CanDrawStrokes();
 }
 
 SkColor BrowserTabStripController::GetFrameColor(
     BrowserFrameActiveState active_state) const {
+  if (!GetFrameView())
+    return SK_ColorWHITE;
   return GetFrameView()->GetFrameColor(active_state);
 }
 
 absl::optional<int> BrowserTabStripController::GetCustomBackgroundId(
     BrowserFrameActiveState active_state) const {
+  if (!GetFrameView())
+    return absl::nullopt;
   return GetFrameView()->GetCustomBackgroundId(active_state);
 }
 
diff --git chrome/browser/ui/views/toolbar/toolbar_view.cc chrome/browser/ui/views/toolbar/toolbar_view.cc
index 4682fa0f74996..099742d04102a 100644
--- chrome/browser/ui/views/toolbar/toolbar_view.cc
+++ chrome/browser/ui/views/toolbar/toolbar_view.cc
@@ -175,12 +175,13 @@ constexpr int kBrowserAppMenuRefreshCollapsedMargin = 2;
 ////////////////////////////////////////////////////////////////////////////////
 // ToolbarView, public:
 
-ToolbarView::ToolbarView(Browser* browser, BrowserView* browser_view)
+ToolbarView::ToolbarView(Browser* browser, BrowserView* browser_view,
+                         absl::optional<DisplayMode> display_mode)
     : AnimationDelegateViews(this),
       browser_(browser),
       browser_view_(browser_view),
       app_menu_icon_controller_(browser->profile(), this),
-      display_mode_(GetDisplayMode(browser)) {
+      display_mode_(display_mode ? *display_mode : GetDisplayMode(browser)) {
   SetID(VIEW_ID_TOOLBAR);
 
   if (display_mode_ == DisplayMode::NORMAL) {
@@ -202,6 +203,19 @@ ToolbarView::~ToolbarView() {
 }
 
 void ToolbarView::Init() {
+#if BUILDFLAG(ENABLE_CEF)
+  using ToolbarButtonType = cef::BrowserDelegate::ToolbarButtonType;
+  auto button_visible = [this](ToolbarButtonType type) {
+    if (this->browser_->cef_delegate()) {
+      return this->browser_->cef_delegate()->IsToolbarButtonVisible(type);
+    }
+    return true;
+  };
+  #define BUTTON_VISIBLE(type) button_visible(ToolbarButtonType::type)
+#else
+  #define BUTTON_VISIBLE(type) true
+#endif
+
 #if defined(USE_AURA)
   // Avoid generating too many occlusion tracking calculation events before this
   // function returns. The occlusion status will be computed only once once this
@@ -211,12 +225,13 @@ void ToolbarView::Init() {
 #endif
   auto location_bar = std::make_unique<LocationBarView>(
       browser_, browser_->profile(), browser_->command_controller(), this,
-      display_mode_ != DisplayMode::NORMAL);
+      display_mode_ != DisplayMode::NORMAL && !browser_->toolbar_overridden());
   // Make sure the toolbar shows by default.
   size_animation_.Reset(1);
 
   std::unique_ptr<DownloadToolbarButtonView> download_button;
-  if (download::IsDownloadBubbleEnabled(browser_->profile())) {
+  if (download::IsDownloadBubbleEnabled(browser_->profile()) &&
+      BUTTON_VISIBLE(kDownload)) {
     download_button =
         std::make_unique<DownloadToolbarButtonView>(browser_view_);
   }
@@ -297,8 +312,10 @@ void ToolbarView::Init() {
     }
   }
   std::unique_ptr<media_router::CastToolbarButton> cast;
-  if (media_router::MediaRouterEnabled(browser_->profile()))
+  if (media_router::MediaRouterEnabled(browser_->profile()) &&
+      BUTTON_VISIBLE(kCast)) {
     cast = media_router::CastToolbarButton::Create(browser_);
+  }
 
   std::unique_ptr<MediaToolbarButtonView> media_button;
   if (base::FeatureList::IsEnabled(media::kGlobalMediaControls)) {
@@ -308,7 +325,8 @@ void ToolbarView::Init() {
 
   std::unique_ptr<send_tab_to_self::SendTabToSelfToolbarIconView>
       send_tab_to_self_button;
-  if (!browser_->profile()->IsOffTheRecord()) {
+  if (!browser_->profile()->IsOffTheRecord() &&
+      BUTTON_VISIBLE(kSendTabToSelf)) {
     send_tab_to_self_button =
         std::make_unique<send_tab_to_self::SendTabToSelfToolbarIconView>(
             browser_view_);
@@ -316,7 +334,7 @@ void ToolbarView::Init() {
 
   std::unique_ptr<SidePanelToolbarButton> side_panel_button;
   std::unique_ptr<SidePanelToolbarContainer> side_panel_toolbar_container;
-  if (browser_view_->unified_side_panel()) {
+  if (browser_view_->unified_side_panel() && BUTTON_VISIBLE(kSidePanel)) {
     if (base::FeatureList::IsEnabled(
             companion::features::kSidePanelCompanion)) {
       side_panel_toolbar_container =
diff --git chrome/browser/ui/views/toolbar/toolbar_view.h chrome/browser/ui/views/toolbar/toolbar_view.h
index c38f2b0545d21..fe9a92b2f610c 100644
--- chrome/browser/ui/views/toolbar/toolbar_view.h
+++ chrome/browser/ui/views/toolbar/toolbar_view.h
@@ -89,7 +89,8 @@ class ToolbarView : public views::AccessiblePaneView,
                 // needs to be displayed.
   };
 
-  ToolbarView(Browser* browser, BrowserView* browser_view);
+  ToolbarView(Browser* browser, BrowserView* browser_view,
+              absl::optional<DisplayMode> display_mode);
   ToolbarView(const ToolbarView&) = delete;
   ToolbarView& operator=(const ToolbarView&) = delete;
   ~ToolbarView() override;