Reland 596ff54335b2a1b393af10657bc4945114f3beed - Split API bundle generation steps

extensions/common/api/schemas.gni

Index: extensions/common/api/schemas.gni
diff --git a/extensions/common/api/schemas.gni b/extensions/common/api/schemas.gni
new file mode 100644
index 0000000000000000000000000000000000000000..2227b716014a0ab66d64afab09b2bea013718934
--- /dev/null
+++ b/extensions/common/api/schemas.gni
@@ -0,0 +1,17 @@
+# 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.
+
+gypi_values = exec_script(
+    "//build/gypi_to_gn.py",
+    [ rebase_path("schemas.gypi") ],
+    "scope",
+    [ "schemas.gypi" ])
+
+if (is_android) {
+  sources = gypi_values.android_schema_files
+} else {
+  sources = gypi_values.main_schema_files
+}
+
+root_namespace = "extensions::core_api::%(namespace)s"