Start work on GN build for content/common

content/public/common/BUILD.gn

Index: content/public/common/BUILD.gn
diff --git a/content/public/common/BUILD.gn b/content/public/common/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..4788b6d15495f1162645acd19f234cbe91fc7d9c
--- /dev/null
+++ b/content/public/common/BUILD.gn
@@ -0,0 +1,14 @@
+# Copyright 2014 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.
+
+import("//content/common/common.gni")
+
+source_set("common") {
+  sources = rebase_path(content_common_gypi_values.public_common_sources,
+                        ".", "//content")
+
+  deps = [
+    "//content/common",
+  ]
+}