Start adding gn build for android_webview

android_webview/common/BUILD.gn

Index: android_webview/common/BUILD.gn
diff --git a/android_webview/common/BUILD.gn b/android_webview/common/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..4be51790174fed0d15fded6cd6fea3ec0e704362
--- /dev/null
+++ b/android_webview/common/BUILD.gn
@@ -0,0 +1,10 @@
+# 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.
+
+import("//chrome/version.gni")
+
+process_version("version") {
+  template_file = "aw_version_info_values.h.version"
+  output = "$root_gen_dir/android_webview/common/aw_version_info_values.h"
+}