Add support for running Linux desktop tests on CI

.ci/Dockerfile-LinuxDesktop

@@ -0,0 +1,19 @@
+FROM cirrusci/flutter:stable
+
+RUN sudo apt-get update -y
+
+RUN sudo apt-get install -y --no-install-recommends gnupg
+
+# Add repo for gcloud sdk and install it
+RUN echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" | \
+    sudo tee -a /etc/apt/sources.list.d/google-cloud-sdk.list
+
+RUN curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | \
+    sudo apt-key --keyring /usr/share/keyrings/cloud.google.gpg add -
+
+RUN sudo apt-get update && sudo apt-get install -y google-cloud-sdk && \
+    gcloud config set core/disable_usage_reporting true && \
+    gcloud config set component_manager/disable_update_check true
+
+# Install Linux desktop requirements.
+RUN sudo apt-get install -y clang make cmake ninja-build rsync pkg-config

.cirrus.yml

@@ -96,6 +96,33 @@ task:
         - export CIRRUS_CHANGE_MESSAGE=`cat /tmp/cirrus_change_message.txt`
         - export CIRRUS_COMMIT_MESSAGE=`cat /tmp/cirrus_commit_message.txt`
 
+task:
+  # don't run on release tags since it creates O(n^2) tasks where n is the number of plugins
+  only_if: $CIRRUS_TAG == ''
+  use_compute_credits: $CIRRUS_USER_COLLABORATOR == 'true' && $CIRRUS_PR == ''
+  container:
+    dockerfile: .ci/Dockerfile-LinuxDesktop
+    cpu: 8
+    memory: 16G
+  env:
+    E2E_PATH: "./packages/e2e"
+  upgrade_script:
+    - flutter channel stable
+    - flutter upgrade
+    - flutter channel master
+    - flutter upgrade
+    - git fetch origin master
+  activate_script: pub global activate flutter_plugin_tools
+  matrix:
+    - name: build-linux+drive-examples
+      install_script:
+        - flutter config --enable-linux-desktop
+      build_script:
+        # TODO(stuartmorgan): Include stable once Linux is supported on stable.
+        - flutter channel master
+        - ./script/incremental_build.sh build-examples --linux
+        - ./script/incremental_build.sh drive-examples --linux
+
 task:
   # don't run on release tags since it creates O(n^2) tasks where n is the number of plugins
   only_if: $CIRRUS_TAG == ''