diff --git content/browser/web_contents/web_contents_impl.cc content/browser/web_contents/web_contents_impl.cc
index 5a683026aaa08..1bab3bb15cc67 100644
--- content/browser/web_contents/web_contents_impl.cc
+++ content/browser/web_contents/web_contents_impl.cc
@@ -3809,6 +3809,12 @@ void WebContentsImpl::Init(const WebContents::CreateParams& params,
       params.main_frame_name, GetOpener(), primary_main_frame_policy,
       base::UnguessableToken::Create());
 
+  if (params.view && params.delegate_view) {
+    view_.reset(params.view);
+    render_view_host_delegate_view_ = params.delegate_view;
+  }
+
+  if (!view_) {
   std::unique_ptr<WebContentsViewDelegate> delegate =
       GetContentClient()->browser()->GetWebContentsViewDelegate(this);
 
@@ -3819,6 +3825,7 @@ void WebContentsImpl::Init(const WebContents::CreateParams& params,
     view_ = CreateWebContentsView(this, std::move(delegate),
                                   &render_view_host_delegate_view_);
   }
+  }
   CHECK(render_view_host_delegate_view_);
   CHECK(view_.get());
 
@@ -4024,6 +4031,9 @@ void WebContentsImpl::RenderWidgetCreated(
                         "render_widget_host", render_widget_host);
   CHECK(!created_widgets_.contains(render_widget_host->GetFrameSinkId()));
   created_widgets_[render_widget_host->GetFrameSinkId()] = render_widget_host;
+
+  observers_.NotifyObservers(
+      &WebContentsObserver::RenderWidgetCreated, render_widget_host);
 }
 
 void WebContentsImpl::RenderWidgetDeleted(
@@ -4925,6 +4935,15 @@ FrameTree* WebContentsImpl::CreateNewWindow(
     create_params.picture_in_picture_options = *(params.pip_options);
   }
 
+  if (delegate_) {
+    delegate_->GetCustomWebContentsView(this,
+                                        params.target_url,
+                                        render_process_id,
+                                        opener->GetRoutingID(),
+                                        &create_params.view,
+                                        &create_params.delegate_view);
+  }
+
   // Check whether there is an available prerendered page for this navigation if
   // this is not for guest. If it exists, take WebContents pre-created for
   // hosting the prerendered page instead of creating new WebContents.
@@ -9486,6 +9505,9 @@ void WebContentsImpl::SetFocusedFrame(FrameTreeNode* node,
   }
 
   CloseListenerManager::DidChangeFocusedFrame(this);
+
+  observers_.NotifyObservers(&WebContentsObserver::OnFrameFocused,
+                             node->current_frame_host());
 }
 
 FrameTree* WebContentsImpl::GetOwnedPictureInPictureFrameTree() {
diff --git content/public/browser/web_contents.h content/public/browser/web_contents.h
index e9c6a19ace431..398d7c806ed4d 100644
--- content/public/browser/web_contents.h
+++ content/public/browser/web_contents.h
@@ -114,10 +114,12 @@ class BrowserPluginGuestDelegate;
 class GuestPageHolder;
 class RenderFrameHost;
 class RenderViewHost;
+class RenderViewHostDelegateView;
 class RenderWidgetHostView;
 class ScreenOrientationDelegate;
 class SiteInstance;
 class WebContentsDelegate;
+class WebContentsView;
 class WebUI;
 struct DropData;
 struct MHTMLGenerationParams;
@@ -278,6 +280,10 @@ class WebContents : public PageNavigator, public base::SupportsUserData {
     network::mojom::WebSandboxFlags starting_sandbox_flags =
         network::mojom::WebSandboxFlags::kNone;
 
+    // Optionally specify the view and delegate view.
+    raw_ptr<content::WebContentsView> view = nullptr;
+    raw_ptr<content::RenderViewHostDelegateView> delegate_view = nullptr;
+
     // Value used to set the last time the WebContents was made active, this is
     // the value that'll be returned by GetLastActiveTimeTicks(). If this is
     // left default initialized then the value is not passed on to the
diff --git content/public/browser/web_contents_delegate.h content/public/browser/web_contents_delegate.h
index 0bab4dd08a28d..5b4334dcef8d2 100644
--- content/public/browser/web_contents_delegate.h
+++ content/public/browser/web_contents_delegate.h
@@ -98,9 +98,11 @@ class EyeDropperListener;
 class FileSelectListener;
 class JavaScriptDialogManager;
 class RenderFrameHost;
+class RenderViewHostDelegateView;
 class RenderWidgetHost;
 class SessionStorageNamespace;
 class SiteInstance;
+class WebContentsView;
 struct ContextMenuParams;
 struct DropData;
 struct MediaPlayerWatchTime;
@@ -366,6 +368,14 @@ class CONTENT_EXPORT WebContentsDelegate {
       const StoragePartitionConfig& partition_config,
       SessionStorageNamespace* session_storage_namespace);
 
+  virtual void GetCustomWebContentsView(
+      WebContents* web_contents,
+      const GURL& target_url,
+      int opener_render_process_id,
+      int opener_render_frame_id,
+      raw_ptr<content::WebContentsView>* view,
+      raw_ptr<content::RenderViewHostDelegateView>* delegate_view) {}
+
   // Notifies the delegate about the creation of a new WebContents. This
   // typically happens when popups are created.
   virtual void WebContentsCreated(WebContents* source_contents,
diff --git content/public/browser/web_contents_observer.h content/public/browser/web_contents_observer.h
index 5e73c1f7cce2f..818a27a47a3db 100644
--- content/public/browser/web_contents_observer.h
+++ content/public/browser/web_contents_observer.h
@@ -248,6 +248,9 @@ class CONTENT_EXPORT WebContentsObserver : public base::CheckedObserver {
   // controlled by the capturing tab.
   virtual void OnCapturedSurfaceControl() {}
 
+  // This method is invoked when a RenderWidget is created.
+  virtual void RenderWidgetCreated(RenderWidgetHost* render_widget_host) {}
+
   // This method is invoked when the `blink::WebView` of the current
   // RenderViewHost is ready, e.g. because we recreated it after a crash.
   virtual void RenderViewReady() {}
@@ -942,6 +945,10 @@ class CONTENT_EXPORT WebContentsObserver : public base::CheckedObserver {
   // WebContents has gained/lost focus.
   virtual void OnFocusChangedInPage(FocusedNodeDetails* details) {}
 
+  // Notification that |render_frame_host| for this WebContents has gained
+  // focus.
+  virtual void OnFrameFocused(RenderFrameHost* render_frame_host) {}
+
   // Notifies that the manifest URL for the main frame changed to
   // |manifest_url|. This will be invoked when a document with a manifest loads
   // or when the manifest URL changes (possibly to nothing). It is not invoked