Make check_gn_headers.py run on Windows

build/check_gn_headers.py

Index: build/check_gn_headers.py
diff --git a/build/check_gn_headers.py b/build/check_gn_headers.py
index fe884db6cb0b8e8253d5be3ac91d59d1c4290211..f3953704d95e1b69acb06e998a9e6542879d073d 100755
--- a/build/check_gn_headers.py
+++ b/build/check_gn_headers.py
@@ -48,7 +48,8 @@ def ParseNinjaDepsOutput(ninja_out):
   """Parse ninja output and get the header files"""
   all_headers = set()
 
-  prefix = '..' + os.sep + '..' + os.sep
+  # Ninja always use "/", even on Windows.

[brucedawson, 2017/06/12 17:38:40]

use-> uses

[wychen, 2017/06/12 21:45:45]

Done.

+  prefix = '../../'
 
   is_valid = False
   for line in ninja_out:
@@ -76,11 +77,14 @@ def GetHeadersFromGN(out_dir, q):
   tmp = None
   ans, err = set(), None
   try:
-    tmp = tempfile.mkdtemp()
+    # Argument |dir| is needed to make sure it's on the same drive on Windows.
+    # dir='' means dir='.', but doesn't introduce an unneeded prefix.
+    tmp = tempfile.mkdtemp(dir='')
     shutil.copy2(os.path.join(out_dir, 'args.gn'),
                  os.path.join(tmp, 'args.gn'))
     # Do "gn gen" in a temp dir to prevent dirtying |out_dir|.
-    subprocess.check_call(['gn', 'gen', tmp, '--ide=json', '-q'])
+    GN_EXE = 'gn.bat' if sys.platform == 'win32' else 'gn'

[brucedawson, 2017/06/12 17:38:40]

Why upper-case for GN_EXE and GCLIENT_EXE? Doesn't the style guide say
lower-case?

[wychen, 2017/06/12 21:45:45]

Done.

+    subprocess.check_call([GN_EXE, 'gen', tmp, '--ide=json', '-q'])
     gn_json = json.load(open(os.path.join(tmp, 'project.json')))
     ans = ParseGNProjectJSON(gn_json, out_dir, tmp)
   except Exception as e:
@@ -116,9 +120,11 @@ def GetDepsPrefixes(q):
   """Return all the folders controlled by DEPS file"""
   prefixes, err = set(), None
   try:
+    GCLIENT_EXE = 'gclient.bat' if sys.platform == 'win32' else 'gclient'
     gclient_out = subprocess.check_output(
-        ['gclient', 'recurse', '--no-progress', '-j1',
-         'python', '-c', 'import os;print os.environ["GCLIENT_DEP_PATH"]'])
+        [GCLIENT_EXE, 'recurse', '--no-progress', '-j1',
+         'python', '-c', 'import os;print os.environ["GCLIENT_DEP_PATH"]'],
+         universal_newlines = True)
     for i in gclient_out.split('\n'):
       if i.startswith('src/'):
         i = i[4:]