Add Build Timer

common.sh

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Common constants for build scripts
 # This must evaluate properly for both /bin/bash and /bin/sh
 
 # All scripts should die on error unless commands are specifically excepted
 # by prefixing with '!' or surrounded by 'set +e' / 'set -e'.
 # TODO: Re-enable this once shflags is less prone to dying.
@@ skipping 411 matching lines @@
 
   # Setup var symlink.
   if [ -h "${dev_image_root}/var" ]; then
     sudo unlink "${dev_image_root}/var"
   elif [ -e "${dev_image_root}/var" ]; then
     die "${dev_image_root}/var should be a symlink if it exists"
   fi
 
   sudo ln -s "${var_target}" "${dev_image_root}/var"
 }
+
+# Get current timestamp. Assumes common.sh runs at startup.
+start_time=$(date +%s)
+
+# Print time elsapsed since start_time.
+print_time_elapsed() {
+  end_time=$(date +%s)
+  elapsed_seconds="$(( $end_time - $start_time ))"
+  minutes="$(( $elapsed_seconds / 60 ))"
+  seconds="$(( $elapsed_seconds % 60 ))"
+  echo "Elapsed time: ${minutes}:${seconds}"
+}