[fuchsia] add support for api level when calling fidlc (#583)

Author: chaselatta

build/fuchsia/fidl_gen_cpp.py

@@ -42,6 +42,7 @@ def main():
   parser.add_argument('--json', dest='json', action='store', required=True)
   parser.add_argument('--fidlgen-output-root', dest='fidlgen_output_root', action='store', required=False)
   parser.add_argument('--output-c-tables', dest='output_c_tables', action='store', required=True)
+  parser.add_argument('--target-api-level', dest='target_api_level', action='store', required=False)
 
   args = parser.parse_args()
 
@@ -59,6 +60,12 @@ def main():
     args.json
   ]
 
+  if args.target_api_level:
+    fidlc_command += [
+      '--available',
+      'fuchsia:{api_level}'.format(api_level=args.target_api_level),
+    ]
+
   # Create an iterator that works on both python3 and python2
   try:
     fidl_files_by_name_iter = list(fidl_files_by_name.items())

build/fuchsia/sdk.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/fuchsia/config.gni")
+
 declare_args() {
   # The path to where GN targets derived from the Fuchsia SDK are instantiated.
   fuchsia_sdk_root = "//build/fuchsia"
@@ -113,6 +115,13 @@ template("_fuchsia_fidl_library") {
       rebase_path("$target_gen_dir/$library_name_slashes/cpp/tables.c"),
     ]
 
+    if (fuchsia_target_api_level != -1) {
+      args += [
+        "--target-api-level",
+        "${fuchsia_target_api_level}",
+      ]
+    }
+
     if (!defined(invoker.only_generate_tables) ||
         !invoker.only_generate_tables) {
       outputs += [