fileSystemProvider: First cut at implementing fileSystemProvider API

chrome/renderer/extensions/file_system_provider_natives.cc

+// Copyright 2013 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 "chrome/renderer/extensions/file_system_provider_natives.h"
+
+#include <string>
+
+#include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/web/WebDOMError.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+fileSystemProviderNatives::fileSystemProviderNatives(
+    ChromeV8Context* context)
+    : ObjectBackedNativeHandler(context) {
+  RouteFunction(
+      "GetDOMError",
+      base::Bind(&fileSystemProviderNatives::GetDOMError,
+                 base::Unretained(this)));
+}
+
+void fileSystemProviderNatives::GetDOMError(

[benwells, 2013/11/08 03:34:31]

This seems like it would be useful to other APIs. Do any other APIs use it?
Maybe you could put it in the same natives file as the file system.

We seem to have a lot of potentially duplicated file system native api
implementation code in the renderer (e.g. file_system, media_galleries...),
maybe we could have file_api_helper_natives or something.

[satorux1, 2013/11/08 03:57:05]

Good idea. Moved to file_system_natives.cc.

+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  if (args.Length() != 2) {
+    NOTREACHED();
+    return;
+  }
+  if (!args[0]->IsString()) {
+    NOTREACHED();
+    return;
+  }
+  if (!args[1]->IsString()) {
+    NOTREACHED();
+    return;
+  }
+
+  std::string name(*v8::String::Utf8Value(args[0]));
+  if (name.empty()) {
+    NOTREACHED();
+    return;
+  }
+  std::string message(*v8::String::Utf8Value(args[1]));
+  // message is optional hence empty is fine.
+
+  blink::WebDOMError dom_error = blink::WebDOMError::create(
+      blink::WebString::fromUTF8(name),
+      blink::WebString::fromUTF8(message));
+  args.GetReturnValue().Set(dom_error.toV8Value());
+}
+
+}  // namespace extensions