chore: add DevTools connection adapter (#434)

This PR adds a small utility class that allows us to proxy a CDP
connection via puppeteer into Chrome DevTools proper.

---------

Co-authored-by: Alex Rudenko <[email protected]>

Author: szuend

src/DevToolsConnectionAdapter.ts

@@ -0,0 +1,41 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {type ConnectionTransport} from 'puppeteer-core';
+
+import {Connection} from '../node_modules/chrome-devtools-frontend/front_end/core/protocol_client/InspectorBackend.js';
+
+/**
+ * Allows a puppeteer {@link ConnectionTransport} to act like a DevTools {@link Connection}.
+ */
+export class DevToolsConnectionAdapter extends Connection {
+  #transport: ConnectionTransport | null;
+  #onDisconnect: ((arg0: string) => void) | null = null;
+
+  constructor(transport: ConnectionTransport) {
+    super();
+    this.#transport = transport;
+    this.#transport.onclose = () => this.#onDisconnect?.('');
+    this.#transport.onmessage = msg => this.onMessage?.(msg);
+  }
+
+  override setOnMessage(onMessage: (arg0: object | string) => void): void {
+    this.onMessage = onMessage;
+  }
+
+  override setOnDisconnect(onDisconnect: (arg0: string) => void): void {
+    this.#onDisconnect = onDisconnect;
+  }
+
+  override sendRawMessage(message: string): void {
+    this.#transport?.send(message);
+  }
+
+  override async disconnect(): Promise<void> {
+    this.#transport?.close();
+    this.#transport = null;
+  }
+}