Add support for MIDL include directories

pylib/gyp/msvs_emulation.py

Index: pylib/gyp/msvs_emulation.py
diff --git a/pylib/gyp/msvs_emulation.py b/pylib/gyp/msvs_emulation.py
index fa97aaf37dbc22f21dfe33bebc3f6db1b6ea60f3..d6292cc76b3dae7720f8f7fea8d74551fa4cd766 100644
--- a/pylib/gyp/msvs_emulation.py
+++ b/pylib/gyp/msvs_emulation.py
@@ -318,6 +318,14 @@ class MsvsSettings(object):
       ('VCCLCompilerTool', 'AdditionalIncludeDirectories'), config, default=[]))
     return [self.ConvertVSMacros(p, config=config) for p in includes]
 
+  def AdjustMidlIncludeDirs(self, midl_include_dirs, config):
+    """Updates midl_include_dirs to expand VS specific paths, and adds any
+    AdditionalIncludeDirectories specified in VCMIDLTool."""
+    config = self._TargetConfig(config)
+    includes = midl_include_dirs + self._Setting(
+      ('VCMIDLTool', 'AdditionalIncludeDirectories'), config, default=[])
+    return [self.ConvertVSMacros(p, config=config) for p in includes]
+
   def GetComputedDefines(self, config):
     """Returns the set of defines that are injected to the defines list based
     on other VS settings."""