[Android] Only write the ordered libraries file when it changes

build/android/gyp/util/build_utils.py

 # 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.
 
 import fnmatch
 import json
 import os
 import pipes
 import shlex
 import shutil
@@ skipping 43 matching lines @@
   # is addressed.
   gyp_string = gyp_string.replace('##', '$')
   return shlex.split(gyp_string)
 
 
 def CheckOptions(options, parser, required=[]):
   for option_name in required:
     if not getattr(options, option_name):
       parser.error('--%s is required' % option_name.replace('_', '-'))
 
+def WriteJson(obj, path, only_if_changed=False):
+  old_dump = None
+  if os.path.exists(path):
+    with open(path, 'r') as oldfile:
+      old_dump = oldfile.read()
+
+  new_dump = json.dumps(obj)
+
+  if not only_if_changed or old_dump != new_dump:
+    with open(path, 'w') as outfile:
+      outfile.write(new_dump)
 
 def ReadJson(path):
   with open(path, 'r') as jsonfile:
     return json.load(jsonfile)
 
 
 # This can be used in most cases like subprocess.check_call. The output,
 # particularly when the command fails, better highlights the command's failure.
 # This call will directly exit on a failure in the subprocess so that no python
 # stacktrace is printed after the output of the failed command.
@@ skipping 36 matching lines @@
 
 def IsTimeStale(output, inputs):
   if not os.path.exists(output):
     return True
 
   output_time = GetModifiedTime(output)
   for input in inputs:
     if GetModifiedTime(input) > output_time:
       return True
   return False