cr: Add support for mac

tools/cr/cr-bash-helpers.sh

 #!/bin/bash
 
 # Copyright 2013 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.
 
 # Source this file into your shell to gain the cr function and tab completion
 # for it
 
 # Make sure we're being sourced (possibly by another script). Check for bash
 # since zsh sets $0 when sourcing.
 if [[ -n "$BASH_VERSION" && "${BASH_SOURCE:-$0}" == "$0" ]]; then
   echo "ERROR: cr-bash-helpers.sh must be sourced."
   exit 1
 fi
 
 READLINK_e=("readlink" "-e")
 if [[ -x `which greadlink` ]]; then
   READLINK_e=("greadlink" "-e")
 fi
 
-cr_base_dir=$(dirname $(${READLINK_e[@]} "${BASH_SOURCE:-$0}"))
+if [[ $(uname) == "Darwin" ]]; then
+  cr_base_dir=$(dirname "${BASH_SOURCE:-$0}")
+else
+  cr_base_dir=$(dirname $(${READLINK_e[@]} "${BASH_SOURCE:-$0}"))
+fi
+
 cr_main="${cr_base_dir}/main.py"
 cr_exec=("PYTHONDONTWRITEBYTECODE=1" "python" "${cr_main}")
 
 # The main entry point to the cr tool.
 # Invokes the python script with pyc files turned off.
 function cr() {
   env ${cr_exec[@]} "$@"
 }
 
 # Attempts to cd to the root/src of the current client.
@@ skipping 12 matching lines @@
   local cur="${COMP_WORDS[COMP_CWORD]}"
   local main="python -B "${cr_main}")"
   local completions="$(env COMP_CWORD=${COMP_CWORD} \
       COMP_WORD=${cur} \
       ${cr_exec[@]})"
   COMPREPLY=( $(compgen -W "${completions}" -- ${cur}) )
 }
 
 # Setup the bash auto complete
 complete -F _cr_complete cr