text: #!/usr/bin/env python
  # Copyright (c) 2014 Google Inc. All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are
  # met:
  #
  #     * Redistributions of source code must retain the above copyright
  # notice, this list of conditions and the following disclaimer.
  #     * Redistributions in binary form must reproduce the above
  # copyright notice, this list of conditions and the following disclaimer
  # in the documentation and/or other materials provided with the
  # distribution.
  #     * Neither the name of Google Inc. nor the names of its
  # contributors may be used to endorse or promote products derived from
  # this software without specific prior written permission.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  import os
  import os.path
  import subprocess
  import sys
  
  from build import devtools_file_hashes
  
  try:
      import json
  except ImportError:
      import simplejson as json
  
  scripts_path = os.path.dirname(os.path.abspath(__file__))
  devtools_path = os.path.dirname(scripts_path)
  blink_source_path = os.path.dirname(devtools_path)
  blink_path = os.path.dirname(blink_source_path)
  chromium_src_path = os.path.dirname(os.path.dirname(blink_path))
  devtools_frontend_path = os.path.join(devtools_path, "front_end")
  images_path = os.path.join(devtools_frontend_path, "Images")
  image_sources_path = os.path.join(images_path, "src")
  hashes_file_name = "optimize_png.hashes"
  hashes_file_path = os.path.join(image_sources_path, hashes_file_name)
  
  file_names = os.listdir(image_sources_path)
  svg_file_paths = [os.path.join(image_sources_path, file_name) for file_name in file_names if file_name.endswith(".svg")]
  svg_file_paths_to_optimize = devtools_file_hashes.files_with_invalid_hashes(hashes_file_path, svg_file_paths)
  svg_file_names = [os.path.basename(file_path) for file_path in svg_file_paths_to_optimize]
  
  
  def check_installed(app_name):
      proc = subprocess.Popen("which %s" % app_name, stdout=subprocess.PIPE, shell=True)
      proc.communicate()
      if proc.returncode != 0:
          print "This script needs \"%s\" to be installed." % app_name
          print "Run sudo gem install image_optim image_optim_pack"
          sys.exit(1)
  
  
  check_installed("image_optim")
  
  
  def optimize_png(file_name):
      png_full_path = os.path.join(images_path, file_name + ".png")
      optimize_command = "image_optim %s" % png_full_path
      proc = subprocess.Popen(optimize_command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True, cwd=chromium_src_path)
      return proc
  
  
  if len(svg_file_names):
      print "%d unoptimized png files found." % len(svg_file_names)
  else:
      print "All png files are already optimized."
      sys.exit()
  
  processes = {}
  for file_name in svg_file_names:
      name = os.path.splitext(file_name)[0]
      name2x = name + "_2x"
      processes[name] = optimize_png(name)
      processes[name2x] = optimize_png(name2x)
  
  for file_name, proc in processes.items():
      (optimize_out, _) = proc.communicate()
      print("Optimization of %s finished: %s" % (file_name, optimize_out))
  
  devtools_file_hashes.update_file_hashes(hashes_file_path, svg_file_paths)
  