[infra] Translate _sources.gypi files to _sources.gni files

runtime/observatory/update_sources.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # Updates the list of Observatory source files.
 
 import os
 import sys
 from datetime import date
 
 def getDir(rootdir, target):
-    sources = []
-    for root, subdirs, files in os.walk(rootdir):
-        subdirs.sort()
-        files.sort()
-        for f in files:
-            sources.append(root + '/' + f)
-    return sources
+  sources = []
+  for root, subdirs, files in os.walk(rootdir):
+    subdirs.sort()
+    files.sort()
+    for f in files:
+      sources.append(root + '/' + f)
+  return sources
+
+HEADER = """# Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+# DO NOT EDIT. This file is generated by update_sources.py in this directory.
+
+# This file contains all dart, css, and html sources for Observatory.
+"""
 
 def main():
-    target = open('observatory_sources.gypi', 'w')
-    target.write('# Copyright (c) ')
-    target.write(str(date.today().year))
-    target.write(', the Dart project authors.  Please see the AUTHORS file\n');
-    target.write('# for details. All rights reserved. Use of this source code is governed by a\n');
-    target.write('# BSD-style license that can be found in the LICENSE file.\n');
-    target.write('\n');
-    target.write('# This file contains all dart, css, and html sources for Observatory.\n');
-    target.write('{\n  \'sources\': [\n')
+  with open('observatory_sources.gni', 'w') as target:
+    target.write(HEADER)
+    target.write('observatory_sources = [\n')
     sources = []
     for rootdir in ['lib', 'web']:
-        sources.extend(getDir(rootdir, target))
+      sources.extend(getDir(rootdir, target))
     sources.sort()
     for s in sources:
-        if (s[-9:] != 'README.md'):
-            target.write('    \'' + s + '\',\n')
-    target.write('  ]\n}\n')
-    target.close()
+      if (s[-9:] != 'README.md'):
+        target.write('  "' + s + '",\n')
+    target.write(']\n')
 
 if __name__ == "__main__":
    main()