Extract re-usable InitializeMediaFoundation()

media/base/win/BUILD.gn

Index: media/base/win/BUILD.gn
diff --git a/media/base/win/BUILD.gn b/media/base/win/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..4888d6f41ceec69af82ec470bb69d05e39306d3b
--- /dev/null
+++ b/media/base/win/BUILD.gn
@@ -0,0 +1,18 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+assert(is_win)
+
+source_set("win") {
+  set_sources_assignment_filter([])
+  sources = [
+    "mf_initializer.cc",
+    "mf_initializer.h",
+  ]
+  set_sources_assignment_filter(sources_assignment_filter)
+  configs += [
+    "//media:media_config",
+    "//media:media_implementation",
+  ]
+}