Skip running GYP if GYP_CHROMIUM_NO_ACTION is set in environment

gyp_libyuv

Index: gyp_libyuv
diff --git a/gyp_libyuv b/gyp_libyuv
index 645d3ad45ca6a684a1583c3ed8dc5a0dec64d8c0..445b924f16b0a814f626eccebb1a2b02e04922ff 100755
--- a/gyp_libyuv
+++ b/gyp_libyuv
@@ -37,6 +37,10 @@ def GetSupplementalFiles():
 if __name__ == '__main__':
   args = sys.argv[1:]
 
+  if int(os.environ.get('GYP_CHROMIUM_NO_ACTION', 0)):
+    print 'Skipping gyp_libyuv due to GYP_CHROMIUM_NO_ACTION env var.'
+    sys.exit(0)
+
   # This could give false positives since it doesn't actually do real option
   # parsing.  Oh well.
   gyp_file_specified = False