[ci] Introduce LUCI versions of Linux desktop platform tests (flutter#4223)

Adds scripts and LUCI targets for the Linux desktop platform test tasks, corresponding to the Cirrus linux-platform_test tasks.

Part of flutter#114373

Author: stuartmorgan-g

.ci.yaml

@@ -498,6 +498,35 @@ targets:
       target_file: linux_build_all_packages.yaml
       channel: stable
 
+  - name: Linux_desktop platform_tests master
+    bringup: true # New target
+    recipe: packages/packages
+    timeout: 30
+    properties:
+      version_file: flutter_master.version
+      target_file: linux_platform_tests.yaml
+      channel: master
+      # Install Chrome as a default handler for schemes for url_launcher.
+      dependencies: >-
+        [
+          {"dependency": "chrome_and_driver", "version": "version:114.0"}
+        ]
+
+  - name: Linux_desktop platform_tests stable
+    bringup: true # New target
+    recipe: packages/packages
+    presubmit: false
+    timeout: 30
+    properties:
+      version_file: flutter_stable.version
+      target_file: linux_platform_tests.yaml
+      channel: stable
+      # Install Chrome as a default handler for schemes for url_launcher.
+      dependencies: >-
+        [
+          {"dependency": "chrome_and_driver", "version": "version:114.0"}
+        ]
+
   ### iOS+macOS tasks ###
   # TODO(stuartmorgan): Move this to ARM once google_maps_flutter has ARM
   # support. `pod lint` makes a synthetic target that doesn't respect the

.ci/scripts/set_default_linux_apps.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+set -e
+
+# Set up a .desktop file pointing to the CIPD-installed Chrome.
+readonly LOCAL_DESKTOP_FILE_DIR=~/.local/share/applications
+mkdir -p "${LOCAL_DESKTOP_FILE_DIR}"
+readonly DESKTOP_FILE_NAME=cipd-chrome.desktop
+readonly CIPD_CHROME_DESKTOP_FILE="${LOCAL_DESKTOP_FILE_DIR}/${DESKTOP_FILE_NAME}"
+cat << EOF > "${CIPD_CHROME_DESKTOP_FILE}"
+[Desktop Entry]
+Version=1.0
+Name=Google Chrome
+GenericName=Web Browser
+Comment=Access the Internet
+Exec=${CHROME_EXECUTABLE} %U
+StartupNotify=true
+Terminal=false
+Icon=google-chrome
+Type=Application
+Categories=Network;WebBrowser;
+MimeType=application/pdf;application/rdf+xml;application/rss+xml;application/xhtml+xml;application/xhtml_xml;application/xml;image/gif;image/jpeg;image/png;image/webp;text/html;text/xml;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/file;
+EOF
+
+# Enable xdg-* commands to work correctly.
+export DESKTOP_SESSION=gnome
+
+# Set Chrome as the default handler for http, https, and file, for url_launcher
+# tests that expect handlers for those schemes.
+xdg-mime default "${DESKTOP_FILE_NAME}" inode/directory
+xdg-settings set default-web-browser "${DESKTOP_FILE_NAME}"

.ci/scripts/xvfb_tool_runner.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+set -e
+
+xvfb-run ./script/tool_runner.sh "$@"

.ci/targets/linux_platform_tests.yaml

@@ -0,0 +1,14 @@
+tasks:
+  - name: prepare tool
+    script: .ci/scripts/prepare_tool.sh
+  - name: set default apps
+    script: .ci/scripts/set_default_linux_apps.sh
+  - name: build examples
+    script: script/tool_runner.sh
+    args: ["build-examples", "--linux"]
+  - name: native test
+    script: .ci/scripts/xvfb_tool_runner.sh
+    args: ["native-test", "--linux"]
+  - name: drive examples
+    script: .ci/scripts/xvfb_tool_runner.sh
+    args: ["drive-examples", "--linux", "--exclude=script/configs/exclude_integration_linux.yaml"]