Add an implementation path option to json_schema_compiler

build/json_schema_compile.gypi

Index: build/json_schema_compile.gypi
diff --git a/build/json_schema_compile.gypi b/build/json_schema_compile.gypi
index 4f1c295e1f803365ba5aac7248c53e5214a35190..0601f0ba28e7a2a7fd404e9f97888ec0a1d2ee1e 100644
--- a/build/json_schema_compile.gypi
+++ b/build/json_schema_compile.gypi
@@ -8,6 +8,7 @@
     #   schema_files: a list of json or IDL files that comprise the api model.
     #   cc_dir: path to generated files
     #   root_namespace: the C++ namespace that all generated files go under
+    #   impl_dir: the root path of api implementations
     # Functions and namespaces can be excluded by setting "nocompile" to true.
     'api_gen_dir': '<(DEPTH)/tools/json_schema_compiler',
     'api_gen': '<(api_gen_dir)/compiler.py',
@@ -47,6 +48,7 @@
         '--destdir=<(SHARED_INTERMEDIATE_DIR)',
         '--namespace=<(root_namespace)',
         '--generator=cpp',
+        '--impl-dir=<(impl_dir)'
       ],
       'message': 'Generating C++ code from <(RULE_INPUT_PATH) json files',
       'process_outputs_as_sources': 1,
@@ -85,6 +87,7 @@
         '--destdir=<(SHARED_INTERMEDIATE_DIR)',
         '--namespace=<(root_namespace)',
         '--generator=cpp',
+        '--impl-dir=<(impl_dir)'
       ],
       'message': 'Generating C++ code from <(RULE_INPUT_PATH) IDL files',
       'process_outputs_as_sources': 1,