Update PPAPI IDL generator to define versioned structs, and unversioned typedef.

ppapi/generators/idl_c_proto.py

Index: ppapi/generators/idl_c_proto.py
diff --git a/ppapi/generators/idl_c_proto.py b/ppapi/generators/idl_c_proto.py
index 861f86f2efbaa8e07d062f40255a4727ceb6f1b0..ba0d37a55da287876d115219992253cb10922137 100644
--- a/ppapi/generators/idl_c_proto.py
+++ b/ppapi/generators/idl_c_proto.py
@@ -498,9 +498,20 @@ class CGen(object):
     out = ''
     build_list = node.GetUniqueReleases(releases)
 
-    # Build the most recent one with comments
-    out = self.DefineStructInternals(node, build_list[-1],
-                                     include_version=False, comment=True)
+    if node.IsA('Interface'):
+      # Build the most recent one versioned, with comments
+      out = self.DefineStructInternals(node, build_list[-1],
+                                       include_version=True, comment=True)
+
+      # Define an unversioned typedef for the most recent version
+      out += '\ntypedef struct %s %s;\n' % (
+          self.GetStructName(node, build_list[-1], include_version=True),
+          self.GetStructName(node, build_list[-1], include_version=False))
+    else:
+      # Build the most recent one versioned, with comments
+      out = self.DefineStructInternals(node, build_list[-1],
+                                       include_version=False, comment=True)
+
 
     # Build the rest without comments and with the version number appended
     for rel in build_list[0:-1]: