[Extensions Bindings] Add ChromeSetting custom type

extensions/renderer/api_custom_types.cc

+// Copyright 2017 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.
+
+#include "extensions/renderer/api_custom_types.h"
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/stringprintf.h"
+#include "extensions/common/extension_api.h"
+#include "extensions/renderer/api_signature.h"
+
+namespace extensions {
+namespace api_custom_types {
+
+const APISignature& GetFunctionSchema(base::StringPiece api_name,
+                                      base::StringPiece type_name,

[Devlin, 2017/02/24 16:19:28]

Cut and paste from storage_area.cc

+                                      base::StringPiece function_name) {
+  using SignatureMap = std::map<std::string, std::unique_ptr<APISignature>>;
+  CR_DEFINE_STATIC_LOCAL(SignatureMap, signatures, ());

[jbroman, 2017/02/24 18:08:45]

Danger, Will Robinson!

IIUC, this could be called from multiple threads, but is unsynchronized. Perhaps
this should be owned by some object that only lives on one thread? (Or if you
must, a thread-local or lock would work.)

[Devlin, 2017/02/24 20:12:28]

Ah, right, forgot that with workers this can be called from multiple threads.

I'll move this to APITypeReferenceMap in a separate CL - in an unrelated patch,
I realized that it'll be useful to have signatures there anyway.

CL to do this: https://codereview.chromium.org/2716883003

+
+  std::string full_name = base::StringPrintf(
+      "%s.%s.%s", api_name.data(), type_name.data(), function_name.data());
+  auto iter = signatures.find(full_name);
+  if (iter != signatures.end())
+    return *iter->second;
+
+  const base::DictionaryValue* full_schema =
+      ExtensionAPI::GetSharedInstance()->GetSchema(api_name.as_string());
+  const base::ListValue* types = nullptr;
+  CHECK(full_schema->GetList("types", &types));
+  const base::DictionaryValue* type_schema = nullptr;
+  for (const auto& type : *types) {
+    const base::DictionaryValue* type_dict = nullptr;
+    CHECK(type->GetAsDictionary(&type_dict));
+    std::string id;
+    CHECK(type_dict->GetString("id", &id));
+    if (id == type_name) {
+      type_schema = type_dict;
+      break;
+    }
+  }
+  CHECK(type_schema);
+  const base::ListValue* type_functions = nullptr;
+  CHECK(type_schema->GetList("functions", &type_functions));
+  const base::ListValue* parameters = nullptr;
+  for (const auto& function : *type_functions) {
+    const base::DictionaryValue* function_dict = nullptr;
+    CHECK(function->GetAsDictionary(&function_dict));
+    std::string name;
+    CHECK(function_dict->GetString("name", &name));
+    if (name == function_name) {
+      CHECK(function_dict->GetList("parameters", &parameters));
+      break;
+    }
+  }
+  CHECK(parameters);
+  auto signature = base::MakeUnique<APISignature>(*parameters);
+  auto raw_signature = signature.get();
+  signatures[full_name] = std::move(signature);
+  return *raw_signature;
+}
+
+}  // namespace api_custom_types
+}  // namespace extensions