Add a snapshot of flutter/engine/src/build to our sdk

build/android/adb_command_line_functions.sh

+#!/bin/bash
+#
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Variables must be set before calling:
+# CMD_LINE_FILE - Path on device to flags file.
+# REQUIRES_SU - Set to 1 if path requires root.
+function set_command_line() {
+  SU_CMD=""
+  if [[ "$REQUIRES_SU" = 1 ]]; then
+    # Older androids accept "su -c", while newer use "su uid".
+    SDK_LEVEL=$(adb shell getprop ro.build.version.sdk | tr -d '\r')
+    # E.g. if no device connected.
+    if [[ -z "$SDK_LEVEL" ]]; then
+      exit 1
+    fi
+    SU_CMD="su -c"
+    if (( $SDK_LEVEL >= 21 )); then
+      SU_CMD="su 0"
+    fi
+  fi
+
+  if [ $# -eq 0 ] ; then
+    # If nothing specified, print the command line (stripping off "chrome ")
+    adb shell "cat $CMD_LINE_FILE 2>/dev/null" | cut -d ' ' -s -f2-
+  elif [ $# -eq 1 ] && [ "$1" = '' ] ; then
+    # If given an empty string, delete the command line.
+    set -x
+    adb shell $SU_CMD rm $CMD_LINE_FILE >/dev/null
+  else
+    # Else set it.
+    set -x
+    adb shell "echo 'chrome $*' | $SU_CMD dd of=$CMD_LINE_FILE"
+    # Prevent other apps from modifying flags (this can create security issues).
+    adb shell $SU_CMD chmod 0664 $CMD_LINE_FILE
+  fi
+}
+