Some initial hookup of offline page request interception

chrome/browser/android/offline_pages/offline_page_request_handler.h

Index: chrome/browser/android/offline_pages/offline_page_request_handler.h
diff --git a/chrome/browser/android/offline_pages/offline_page_request_handler.h b/chrome/browser/android/offline_pages/offline_page_request_handler.h
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+// 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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_HANDLER_H_
+#define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_HANDLER_H_
+
+#include "base/macros.h"
+#include "base/supports_user_data.h"
+#include "content/public/common/resource_type.h"
+
+namespace net {
+class NetworkDelegate;
+class URLRequest;
+class URLRequestInterceptor;
+class URLRequestJob;
+}
+
+namespace offline_pages {
+
+// Class for servicing requests based on their offline information. Created one
+// per URLRequest and attached to each request.
+//
+// For each supported profile, OfflinePageRequestHandler::CreateInterceptor
+// should be called once to install the custom interceptor.
+//
+// For each request:
+// 1) When a request is starting, OfflinePageRequestHandler::InitializeHandler
+//    will be called to create a new handler and attach to the request.
+// 2) When a request is being processed, MaybeInterceptRequest of custom
+//    interceptor will be inquired.
+//    2.1) If the attached OfflinePageRequestHandler for the request is found,
+//         delegate to OfflinePageRequestHandler::MaybeCreateJob to do the work.
+//         2.1.1) Do immediate checks for those scenarios that the interception
+//                is not needed. Bail out if so.
+//         2.1.2) Start an async task to try to find the offline page.
+//         2.1.3) Return a custom URLRequestJob that is put on hold to wait
+//                for the result of finding offline page.
+//    2.2) Otherwise, bail out without interception.
+class OfflinePageRequestHandler : public base::SupportsUserData::Data {
+ public:
+  // Attaches a newly created handler if the given |request| needs to
+  // be handled by offline pages.
+  static void InitializeHandler(net::URLRequest* request,
+                                content::ResourceType resource_type);
+
+  // Returns the handler attached to |request|. This may return null if no
+  // handler is attached.
+  static OfflinePageRequestHandler* GetHandler(net::URLRequest* request);
+
+  // Creates a protocol interceptor for offline pages. Created one per
+  // supported, i.e. non-incognito, profile.
+  // |profile_id|, which identifies the profile, is passed as a void* to ensure
+  // it's not accidently used on the IO thread.
+  static std::unique_ptr<net::URLRequestInterceptor> CreateInterceptor(
+      void* profile_id);
+
+  ~OfflinePageRequestHandler() override;
+
+  net::URLRequestJob* MaybeCreateJob(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate,
+      void* profile_id);
+
+ private:
+  OfflinePageRequestHandler();
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageRequestHandler);
+};
+
+}  // namespace offline_pages
+
+#endif // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_HANDLER_H_