Update log-dump.sh for Windows nodes.

Tested:
```
$ PROJECT=${CLOUDSDK_CORE_PROJECT} KUBERNETES_SKIP_CONFIRM=y NUM_NODES=2 \
  NUM_WINDOWS_NODES=2 KUBE_GCE_ENABLE_IP_ALIASES=true go run \
  ./hack/e2e.go -- --up
$ cluster/log-dump/log-dump.sh
$ ls _artifacts
```

And with: NUM_NODES=2 NUM_WINDOWS_NODES=0; NUM_NODES=0 NUM_WINDOWS_NODES=2

cluster/log-dump/log-dump.sh

@@ -52,6 +52,10 @@ readonly initd_logfiles="docker/log"
 readonly supervisord_logfiles="kubelet.log supervisor/supervisord.log supervisor/kubelet-stdout.log supervisor/kubelet-stderr.log supervisor/docker-stdout.log supervisor/docker-stderr.log"
 readonly systemd_services="kubelet kubelet-monitor kube-container-runtime-monitor ${LOG_DUMP_SYSTEMD_SERVICES:-docker}"
 readonly dump_systemd_journal="${LOG_DUMP_SYSTEMD_JOURNAL:-false}"
+# Log files found in WINDOWS_LOGS_DIR on Windows nodes:
+readonly windows_node_logfiles="kubelet.log kube-proxy.log docker.log"
+# Log files found in other directories on Windows nodes:
+readonly windows_node_otherfiles="C:\\Windows\\MEMORY.dmp"
 
 # Limit the number of concurrent node connections so that we don't run out of
 # file descriptors for large clusters.
@@ -195,6 +199,66 @@ function save-logs() {
     copy-logs-from-node "${node_name}" "${dir}" "${files}"
 }
 
+# Saves a copy of the Windows Docker event log to ${WINDOWS_LOGS_DIR}\docker.log
+# on node $1.
+function export-windows-docker-event-log() {
+    local -r node="${1}"
+
+    local -r powershell_cmd="powershell.exe -Command \$log=\$(Get-EventLog -LogName Application -Source Docker); Set-Content '${WINDOWS_LOGS_DIR}\\docker.log' \$log.Message"
+
+    # Retry up to 3 times to allow ssh keys to be properly propagated and
+    # stored.
+    for retry in {1..3}; do
+      if gcloud compute ssh --project "${PROJECT}" --zone "${ZONE}" "${node}" \
+        --command "$powershell_cmd"; then
+        break
+      else
+        sleep 10
+      fi
+    done
+}
+
+# Save log files and serial console output from Windows node $1 into local
+# directory $2.
+# This function shouldn't ever trigger errexit.
+function save-logs-windows() {
+    local -r node="${1}"
+    local -r dest_dir="${2}"
+
+    if [[ ! "${gcloud_supported_providers}" =~ "${KUBERNETES_PROVIDER}" ]]; then
+      echo "Not saving logs for ${node}, Windows log dumping requires gcloud support"
+      return
+    fi
+
+    export-windows-docker-event-log "${node}"
+
+    local remote_files=()
+    for file in ${windows_node_logfiles[@]}; do
+      remote_files+=( "${WINDOWS_LOGS_DIR}\\${file}" )
+    done
+    remote_files+=( "${windows_node_otherfiles[@]}" )
+
+    # TODO(pjh, yujuhong): handle rotated logs and copying multiple files at the
+    # same time.
+    for remote_file in ${remote_files[@]}; do
+      # Retry up to 3 times to allow ssh keys to be properly propagated and
+      # stored.
+      for retry in {1..3}; do
+        if gcloud compute scp --recurse --project "${PROJECT}" \
+          --zone "${ZONE}" "${node}:${remote_file}" "${dest_dir}" \
+          > /dev/null; then
+          break
+        else
+          sleep 10
+        fi
+      done
+    done
+
+    # Serial port 1 contains the Windows console output.
+    gcloud compute instances get-serial-port-output --project "${PROJECT}" \
+      --zone "${ZONE}" --port 1 "${node}" > "${dest_dir}/serial-1.log" || true
+}
+
 # Execute a command in container $2 on node $1.
 # Uses docker because the container may not ordinarily permit direct execution.
 function run-in-docker-container() {
@@ -247,8 +311,13 @@ function dump_masters() {
   fi
 }
 
+# Dumps logs from nodes in the cluster. Linux nodes to dump logs from can be
+# specified via $1 or $use_custom_instance_list. If not specified then the nodes
+# to dump logs for will be detected using detect-node-names(); if Windows nodes
+# are present then they will be detected and their logs will be dumped too.
 function dump_nodes() {
   local node_names=()
+  local windows_node_names=()
   if [[ -n "${1:-}" ]]; then
     echo "Dumping logs for nodes provided as args to dump_nodes() function"
     node_names=( "$@" )
@@ -264,9 +333,12 @@ function dump_nodes() {
     if [[ -n "${NODE_NAMES:-}" ]]; then
       node_names=( "${NODE_NAMES[@]}" )
     fi
+    if [[ -n "${WINDOWS_NODE_NAMES:-}" ]]; then
+      windows_node_names=( "${WINDOWS_NODE_NAMES[@]}" )
+    fi
   fi
 
-  if [[ "${#node_names[@]}" == 0 ]]; then
+  if [[ "${#node_names[@]}" == 0 && "${#windows_node_names[@]}" == 0 ]]; then
     echo "No nodes found!"
     return
   fi
@@ -276,24 +348,31 @@ function dump_nodes() {
     node_logfiles_all="${node_logfiles_all} ${hollow_node_logfiles}"
   fi
 
-  nodes_selected_for_logs=()
+  linux_nodes_selected_for_logs=()
   if [[ -n "${LOGDUMP_ONLY_N_RANDOM_NODES:-}" ]]; then
     # We randomly choose 'LOGDUMP_ONLY_N_RANDOM_NODES' many nodes for fetching logs.
     for index in `shuf -i 0-$(( ${#node_names[*]} - 1 )) -n ${LOGDUMP_ONLY_N_RANDOM_NODES}`
     do
-      nodes_selected_for_logs+=("${node_names[$index]}")
+      linux_nodes_selected_for_logs+=("${node_names[$index]}")
     done
   else
-    nodes_selected_for_logs=( "${node_names[@]}" )
+    linux_nodes_selected_for_logs=( "${node_names[@]}" )
   fi
+  all_selected_nodes=( "${linux_nodes_selected_for_logs[@]}" )
+  all_selected_nodes+=( "${windows_node_names[@]}" )
 
   proc=${max_dump_processes}
-  for node_name in "${nodes_selected_for_logs[@]}"; do
+  for i in "${!all_selected_nodes[@]}"; do
+    node_name="${all_selected_nodes[$i]}"
     node_dir="${report_dir}/${node_name}"
     mkdir -p "${node_dir}"
-    # Save logs in the background. This speeds up things when there are
-    # many nodes.
-    save-logs "${node_name}" "${node_dir}" "${node_logfiles_all}" "${node_systemd_services}" &
+    if [[ "${i}" -lt "${#linux_nodes_selected_for_logs[@]}" ]]; then
+      # Save logs in the background. This speeds up things when there are
+      # many nodes.
+      save-logs "${node_name}" "${node_dir}" "${node_logfiles_all}" "${node_systemd_services}" &
+    else
+      save-logs-windows "${node_name}" "${node_dir}" &
+    fi
 
     # We don't want to run more than ${max_dump_processes} at a time, so
     # wait once we hit that many nodes. This isn't ideal, since one might
@@ -311,6 +390,9 @@ function dump_nodes() {
 }
 
 # Collect names of nodes which didn't run logexporter successfully.
+# This function examines NODE_NAMES but not WINDOWS_NODE_NAMES since logexporter
+# does not run on Windows nodes.
+#
 # Note: This step is O(#nodes^2) as we check if each node is present in the list of succeeded nodes.
 # Making it linear would add code complexity without much benefit (as it just takes ~1s for 5k nodes).
 # Assumes:
@@ -328,6 +410,8 @@ function find_non_logexported_nodes() {
   done
 }
 
+# This function examines NODE_NAMES but not WINDOWS_NODE_NAMES since logexporter
+# does not run on Windows nodes.
 function dump_nodes_with_logexporter() {
   if [[ -n "${use_custom_instance_list}" ]]; then
     echo "Dumping logs for nodes provided by log_dump_custom_get_instances() function"
@@ -446,10 +530,16 @@ function detect_node_failures() {
   fi
 
   detect-node-names
-  if [ -z "${INSTANCE_GROUPS:-}" ]; then
+  if [[ "${KUBERNETES_PROVIDER}" == "gce" ]]; then
+    local all_instance_groups=(${INSTANCE_GROUPS[@]} ${WINDOWS_INSTANCE_GROUPS[@]})
+  else
+    local all_instance_groups=(${INSTANCE_GROUPS[@]})
+  fi
+
+  if [ -z "${all_instance_groups:-}" ]; then
     return
   fi
-  for group in "${INSTANCE_GROUPS[@]}"; do
+  for group in "${all_instance_groups[@]}"; do
     local creation_timestamp=$(gcloud compute instance-groups managed describe \
                               "${group}" \
                               --project "${PROJECT}" \