Add experimental code behind a flag for Content Size Policy

content/browser/loader/content_size_resource_handler.h

Index: content/browser/loader/content_size_resource_handler.h
diff --git a/content/browser/loader/content_size_resource_handler.h b/content/browser/loader/content_size_resource_handler.h
new file mode 100644
index 0000000000000000000000000000000000000000..38a3dba4b760d6c513f49b5826fd365bafccfce3
--- /dev/null
+++ b/content/browser/loader/content_size_resource_handler.h
@@ -0,0 +1,46 @@
+// Copyright 2016 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_LOADER_CONTENT_SIZE_RESOURCE_HANDLER_H_
+#define CONTENT_BROWSER_LOADER_CONTENT_SIZE_RESOURCE_HANDLER_H_
+
+#include <map>
+
+#include "base/macros.h"
+#include "content/browser/loader/global_routing_id.h"
+#include "content/browser/loader/layered_resource_handler.h"
+#include "net/url_request/url_request_status.h"
+#include "url/gurl.h"
+
+namespace net {
+class URLRequest;
+}
+
+namespace content {
+
+class ContentSizeResourceHandlerManager;
+
+class ContentSizeResourceHandler : public LayeredResourceHandler {
+ public:
+  ContentSizeResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
+                             net::URLRequest* request,
+                             ContentSizeResourceHandlerManager* manager);
+  ~ContentSizeResourceHandler() override;
+
+ private:
+  // ResourceHandler:
+  bool OnWillStart(const GURL&, bool* defer) override;
+  bool OnReadCompleted(int bytes_read, bool* defer) override;
+  void OnResponseCompleted(const net::URLRequestStatus& status,
+                           const std::string& security_info,
+                           bool* defer) override;
+
+  ContentSizeResourceHandlerManager* manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSizeResourceHandler);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_CONTENT_SIZE_RESOURCE_HANDLER_H_