Silence uninteresting proguard output.

build/android/gyp/proguard.py

 #!/usr/bin/env python
 #
 # 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 optparse
 import os
 import sys
 
@@ skipping 10 matching lines @@
   # proguard does its own dependency checking, which can be avoided by deleting
   # the output.
   if os.path.exists(options.output_path):
     os.remove(options.output_path)
   proguard_cmd = ['java', '-jar',
                   options.proguard_path,
                   '-injars', injars,
                   '-outjars', outjars,
                   '-libraryjars', libraryjars,
                   '@' + options.proguard_config]
-  build_utils.CheckOutput(proguard_cmd, print_stdout=True)
+  build_utils.CheckOutput(proguard_cmd, print_stdout=True,
+                          stdout_filter=FilterProguardOutput)
+
+
+def FilterProguardOutput(output):
+  '''ProGuard outputs boring stuff to stdout (proguard version, jar path, etc)
+  as well as interesting stuff (notes, warnings, etc). If stdout is entirely
+  boring, this method suppresses the output.
+  '''
+  ignore_patterns = [
+    'ProGuard, version ',
+    'Reading program jar [',
+    'Reading library jar [',
+    'Preparing output jar [',
+    '  Copying resources from program jar [',
+  ]
+  for line in output.splitlines():
+    for pattern in ignore_patterns:
+      if line.startswith(pattern):
+        break
+    else:
+      # line doesn't match any of the patterns; it's probably something worth
+      # printing out.
+      return output
+  return ''
 
 
 def main(args):
   args = build_utils.ExpandFileArgs(args)
   parser = optparse.OptionParser()
   build_utils.AddDepfileOption(parser)
   parser.add_option('--proguard-path',
                     help='Path to the proguard executable.')
   parser.add_option('--input-path',
                     help='Path to the .jar file proguard should run on.')
@@ skipping 12 matching lines @@
     build_utils.WriteDepfile(
         options.depfile,
         build_utils.GetPythonDependencies())
 
   if options.stamp:
     build_utils.Touch(options.stamp)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))