diff -r 000000000000 -r 6474c204b198 config/makefiles/xpidl/Makefile.in
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/config/makefiles/xpidl/Makefile.in	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,70 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+STANDALONE_MAKEFILE := 1
+
+include $(topsrcdir)/config/rules.mk
+
+# Building XPIDLs effectively consists of two steps:
+#
+#   1) Staging all .idl files to a common directory.
+#   2) Doing everything with the .idl files.
+#
+# Each .idl file is processed into a .h file and typelib information.
+# The .h file shares the same stem as the input file and is installed
+# in the common headers include directory.
+#
+# XPIDL files are logically grouped together by modules. The typelib
+# information for all XPIDLs in the same module is linked together into
+# an .xpt file having the name of the module.
+#
+# As an optimization to reduce overall CPU usage, we process all .idl
+# belonging to a module with a single command invocation. This prevents
+# redundant parsing of .idl files and significantly reduces CPU cycles.
+#
+# Future improvement: Headers are currently written to a local directory then
+# installed in the distribution directory. It is preferable to write headers
+# directly into the distribution directory. However, PGO builds remove the dist
+# directory via rm -rf (with no regards to manifests). Since the cost of
+# processing XPIDL files is not trivial, it is preferrable to cache the headers
+# and reinstall them rather than regenerate them. Ideally the dist pruning is
+# performed with manifests. At that time we can write headers directly to the
+# dist directory.
+
+# For dependency files.
+idl_deps_dir := .deps
+
+# Where we put our final, linked .xpt files.
+idl_xpt_dir := xpt
+
+dist_idl_dir := $(DIST)/idl
+dist_include_dir := $(DIST)/include
+process_py := $(topsrcdir)/python/mozbuild/mozbuild/action/xpidl-process.py
+
+# TODO we should use py_action, but that would require extra directories to be
+# in the virtualenv.
+idlprocess := $(PYTHON_PATH) $(PLY_INCLUDE) -I$(IDL_PARSER_DIR) -I$(IDL_PARSER_CACHE_DIR) \
+    $(process_py) --cache-dir $(IDL_PARSER_CACHE_DIR) $(dist_idl_dir) \
+        $(dist_include_dir) $(idl_xpt_dir) $(idl_deps_dir)
+
+ifdef LIBXUL_SDK
+idlprocess += -I$(LIBXUL_SDK)/idl
+endif
+
+xpidl_modules := @xpidl_modules@
+
+@xpidl_rules@
+
+linked_xpt_files := $(addprefix $(idl_xpt_dir)/,$(addsuffix .xpt,$(xpidl_modules)))
+depends_files := $(foreach root,$(xpidl_modules),$(idl_deps_dir)/$(root).pp)
+
+GARBAGE += $(linked_xpt_files) $(depends_files)
+
+xpidl:: $(linked_xpt_files)
+
+$(linked_xpt_files): $(process_py) $(call mkdir_deps,$(idl_deps_dir) $(dist_include_dir) $(idl_xpt_dir))
+
+$(call include_deps,$(depends_files))
+
+.PHONY: xpidl