fix: handle remote-debugging-port=0 correctly (#17800)

By default the Chromedriver will send remote-debugging-port=0 to let the
browser choose a free port to listen on.  The chosen port is written to
a known file in the user data dir that is passed to the app through the
CLI.

This PR does two things.

1. Correctly passes the USER_DATA_DIR to the remote debugging server so
it knows where to write the file
2. Adds support for --user-data-dir as we did not support that CLI
argument and Chromedriver relies on being able to tell the "browser"
where to write this file.

Fixes #17354

atom/browser/ui/devtools_manager_delegate.cc

@@ -8,9 +8,11 @@
 #include <utility>
 #include <vector>
 
+#include "atom/browser/atom_paths.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
+#include "base/path_service.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ -67,7 +69,7 @@ std::unique_ptr<content::DevToolsSocketFactory> CreateSocketFactory() {
     int temp_port;
     std::string port_str =
         command_line.GetSwitchValueASCII(switches::kRemoteDebuggingPort);
-    if (base::StringToInt(port_str, &temp_port) && temp_port > 0 &&
+    if (base::StringToInt(port_str, &temp_port) && temp_port >= 0 &&
         temp_port < 65535) {
       port = temp_port;
     } else {
@@ -84,8 +86,10 @@ std::unique_ptr<content::DevToolsSocketFactory> CreateSocketFactory() {
 
 // static
 void DevToolsManagerDelegate::StartHttpHandler() {
+  base::FilePath user_dir;
+  base::PathService::Get(DIR_USER_DATA, &user_dir);
   content::DevToolsAgentHost::StartRemoteDebuggingServer(
-      CreateSocketFactory(), base::FilePath(), base::FilePath());
+      CreateSocketFactory(), user_dir, base::FilePath());
 }
 
 DevToolsManagerDelegate::DevToolsManagerDelegate() {}

default_app/main.ts

@@ -102,9 +102,7 @@ function loadApplicationPackage (packagePath: string) {
       } else if (packageJson.name) {
         app.setName(packageJson.name)
       }
-      app.setPath('userData', path.join(app.getPath('appData'), app.getName()))
-      app.setPath('userCache', path.join(app.getPath('cache'), app.getName()))
-      app.setAppPath(packagePath)
+      app._setDefaultAppPaths(packagePath)
     }
 
     try {

lib/browser/api/app.ts

@@ -57,6 +57,21 @@ app.isPackaged = (() => {
   return execFile !== 'electron'
 })()
 
+app._setDefaultAppPaths = (packagePath) => {
+  // Set the user path according to application's name.
+  app.setPath('userData', path.join(app.getPath('appData'), app.getName()))
+  app.setPath('userCache', path.join(app.getPath('cache'), app.getName()))
+  app.setAppPath(packagePath)
+
+  // Add support for --user-data-dir=
+  const userDataDirFlag = '--user-data-dir='
+  const userDataArg = process.argv.find(arg => arg.startsWith(userDataDirFlag))
+  if (userDataArg) {
+    const userDataDir = userDataArg.substr(userDataDirFlag.length)
+    if (path.isAbsolute(userDataDir)) app.setPath('userData', userDataDir)
+  }
+}
+
 if (process.platform === 'darwin') {
   const setDockMenu = app.dock.setMenu
   app.dock.setMenu = (menu) => {

lib/browser/init.ts

@@ -151,10 +151,7 @@ if (packageJson.v8Flags != null) {
   v8.setFlagsFromString(packageJson.v8Flags)
 }
 
-// Set the user path according to application's name.
-app.setPath('userData', path.join(app.getPath('appData'), app.getName()))
-app.setPath('userCache', path.join(app.getPath('cache'), app.getName()))
-app.setAppPath(packagePath)
+app._setDefaultAppPaths(packagePath)
 
 // Load the chrome devtools support.
 require('@electron/internal/browser/chrome-devtools')

typings/internal-electron.d.ts

@@ -13,6 +13,7 @@ declare namespace Electron {
   }
 
   interface App {
+    _setDefaultAppPaths(packagePath: string | null): void;
     setVersion(version: string): void;
     setDesktopName(name: string): void;
     setAppPath(path: string | null): void;