Generate externs automatically from json/idl files.

tools/json_schema_compiler/create_externs.sh

Index: tools/json_schema_compiler/create_externs.sh
diff --git a/tools/json_schema_compiler/create_externs.sh b/tools/json_schema_compiler/create_externs.sh
new file mode 100755
index 0000000000000000000000000000000000000000..f86bcbc6d545d163d24d042e70636a3e5638445b
--- /dev/null
+++ b/tools/json_schema_compiler/create_externs.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+schema_compiler_dir=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)
+chromium_src_dir="${schema_compiler_dir}/../.."
+
+set -e
+
+for f in ${chromium_src_dir}/chrome/common/extensions/api/*.idl; do
+  "${schema_compiler_dir}/compiler.py" "${f}" \
+      --root=${chromium_src_dir} \
+      --generator=externs
+      # Just printing to stdout for now
+done