Create a proprietary scheme for loading web-accessible resources.

content/browser/resource_protocol.h

+// 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.
+
+#ifndef CONTENT_BROWSER_RESOURCE_PROTOCOL_H_
+#define CONTENT_BROWSER_RESOURCE_PROTOCOL_H_
+
+#include <map>
+#include <utility>
+
+#include "content/common/content_export.h"
+#include "net/url_request/url_request_job_factory.h"
+#include "ui/base/layout.h"
+
+namespace content {
+
+class ContentClient;
+
+class CONTENT_EXPORT ResourceProtocolHandler
+    : public net::URLRequestJobFactory::ProtocolHandler {
+ public:
+  // Uses the global content client to fetch resources.
+  ResourceProtocolHandler();
+
+  // Uses the provided content client to fetch resources (for testing).
+  ResourceProtocolHandler(ContentClient* content_client);
+
+  ~ResourceProtocolHandler() override;
+
+  // Warning: calling this method exposes a resource to all web content.
+  // Carefully consider whether the resource could be used for XSS before
+  // registering it.

[davidben, 2014/11/19 00:21:21]

What are resource_id, scale_factor, and content_type in this context? (Document
in comment.)

[jbroman, 2014/11/19 15:06:54]

Done.

+  void RegisterResource(const std::string& host,
+                        const std::string& path,
+                        int resource_id,
+                        ui::ScaleFactor scale_factor,
+                        const std::string& content_type);
+
+  // Overridden from net::URLRequestJobFactory::ProtocolHandler:
+  net::URLRequestJob* MaybeCreateJob(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate) const override;
+  bool IsSafeRedirectTarget(const GURL& location) const override;
+
+  // Public for the URLRequestJob subclass.
+  struct WebAccessibleResource {
+    int resource_id;
+    ui::ScaleFactor scale_factor;
+    std::string content_type;
+  };
+
+ private:
+  ContentClient* content_client_;
+  std::map<std::pair<std::string, std::string>, WebAccessibleResource>

[davidben, 2014/11/19 00:21:21]

I'd either add a comment or a dedicated struct so it's clear what the two
components of the pair are.

[jbroman, 2014/11/19 15:06:54]

Done.

+      resources_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RESOURCE_PROTOCOL_H_