Add config to test android_instrumentation_test samples (#246)

buildkite/install-android-sdk.sh

diff --git a/buildkite/install-android-sdk.sh b/buildkite/install-android-sdk.sh
index 7de287d..0547f8f 100755
--- a/buildkite/install-android-sdk.sh
+++ b/buildkite/install-android-sdk.sh
@@ -38,6 +38,8 @@
 
 # This should be kept in sync with mac/mac-android.sh.
 tools/bin/sdkmanager \
+  "emulator" \
+  "system-images;android-23;default;x86" \
   "platform-tools" \
   "build-tools;27.0.3" \
   "platforms;android-24" \

buildkite/pipelines/android-testing-postsubmit.yml

diff --git a/buildkite/pipelines/android-testing-postsubmit.yml b/buildkite/pipelines/android-testing-postsubmit.yml
new file mode 100644
index 0000000..68cbf65
--- /dev/null
+++ b/buildkite/pipelines/android-testing-postsubmit.yml
@@ -0,0 +1,17 @@
+# https://github.com/googlesamples/android-testing#experimental-bazel-support
+---
+platforms:
+  ubuntu1404:
+    build_targets:
+    - "//ui/..."
+    test_flags:
+    - "--spawn_strategy=local" # Required due to unified launcher bug
+    test_targets:
+    - "//ui/..."
+  ubuntu1604:
+    build_targets:
+    - "//ui/..."
+    test_flags:
+    - "--spawn_strategy=local" # Required due to unified launcher bug
+    test_targets:
+    - "//ui/..."

buildkite/setup-ubuntu.sh

diff --git a/buildkite/setup-ubuntu.sh b/buildkite/setup-ubuntu.sh
index 3c7afd8..08ce694 100755
--- a/buildkite/setup-ubuntu.sh
+++ b/buildkite/setup-ubuntu.sh
@@ -70,5 +70,8 @@
 
   # Required by our infrastructure.
   lvm2
+
+  # Required by Android projects using the Skylark maven_{jar, aar} rules
+  maven
 )
 apt-get -qqy install "${packages[@]}" > /dev/null