Make Win runtime DLLs writeable before overwriting

gyp_skia

Index: gyp_skia
diff --git a/gyp_skia b/gyp_skia
index 91d93ca97fd3d8765915912ddb5dd4b8d887d683..ed6d38376fe0465d01c73f43e9477554c287ff36 100755
--- a/gyp_skia
+++ b/gyp_skia
@@ -13,6 +13,7 @@ import glob
 import os
 import platform
 import shlex
+import stat
 import sys
 
 script_dir = os.path.abspath(os.path.dirname(__file__))
@@ -90,7 +91,7 @@ if __name__ == '__main__':
     print ('%s environment variable not set, using default, %s' %
            (ENVVAR_GYP_GENERATORS, default_gyp_generators))
 
-  vs2013_runtime_dll_dirs = None
+  vs_runtime_dll_dirs = None
   if os.getenv('CHROME_HEADLESS', '0') == '1':
     if sys.platform.startswith('win') or sys.platform.startswith('cygwin'):
       chrome_path = os.getenv('CHROME_PATH')
@@ -98,7 +99,7 @@ if __name__ == '__main__':
       sys.path.append(os.path.join(chrome_path, 'build'))
       sys.path.append(os.path.join(chrome_path, 'tools'))
       import vs_toolchain
-      vs2013_runtime_dll_dirs = \
+      vs_runtime_dll_dirs = \
           vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
 
   # Set CWD to the directory containing this script.
@@ -127,7 +128,8 @@ if __name__ == '__main__':
   args.extend(['--depth', '.'])
 
   # Tell gyp to write the build files into output_dir.
-  args.extend(['--generator-output', os.path.abspath(get_output_dir())])
+  out_dir = os.path.abspath(get_output_dir())
+  args.extend(['--generator-output', out_dir])
 
   # Tell ninja to write its output into the same directory.
   args.extend(['-Goutput_dir=%s' % gyp_output_dir])
@@ -158,8 +160,15 @@ if __name__ == '__main__':
 
   # This code is copied from Chrome's build/gyp_chromium. It's not clear why
   # the *_runtime variables are reversed.
-  if vs2013_runtime_dll_dirs:
-    x64_runtime, x86_runtime = vs2013_runtime_dll_dirs
+  if vs_runtime_dll_dirs:
+    # The DLLs might be read-only, which will cause an error when attempting to
+    # overwrite them. Make them writeable first.
+    for path, dirs, files in os.walk(out_dir):
+      for f in files:
+        if f.endswith('.dll'):
+          os.chmod(os.path.join(path, f), stat.S_IWRITE)
+
+    x64_runtime, x86_runtime = vs_runtime_dll_dirs
     vs_toolchain.CopyVsRuntimeDlls(
-        os.path.join(os.getenv('CHROME_PATH'), get_output_dir()),
+        os.path.join(os.getenv('CHROME_PATH'), out_dir),
         (x86_runtime, x64_runtime))