Implement offline mode behind a flag

content/browser/loader/offline_policy.cc

+// Copyright (c) 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 "content/browser/loader/offline_policy.h"
+
+#include "base/command_line.h"
+#include "content/common/resource_messages.h"
+#include "content/public/common/content_switches.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_response_info.h"
+#include "net/url_request/url_request.h"
+
+namespace content {
+
+OfflinePolicy::OfflinePolicy() {}
+
+OfflinePolicy::~OfflinePolicy() {}
+
+int OfflinePolicy::OfflineLoadFlags(
+    int child_id, int route_id, int current_flags,
+    ResourceType::Type resource_type) {
+
+  // Don't do anything if offline mode is disabled.
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableOfflineCacheAccess))
+    return 0;
+
+  // If a consumer has requested something contradictory, it wins; we
+  // don't modify the load flags.
+  if (current_flags &
+      (LOAD_BYPASS_CACHE | LOAD_PREFERRING_CACHE | LOAD_ONLY_FROM_CACHE |
+       LOAD_FROM_CACHE_IF_OFFLINE | LOAD_DISABLE_CACHE)) {
+    return;
+  }
+
+  std::pair<int, int> key(std::make_pair(child_id, route_id));
+  // std::map::insert just returns an existing element if it already exists.
+  const RouteMap::iterator it(
+      offline_state_map_.insert(std::make_pair(key, ROUTE_INIT)).first);
+
+  if (resource_type == ResourceType::MAIN_FRAME)
+    it->second = ROUTE_INIT;
+
+  switch(it->second) {
+    case ROUTE_INIT:
+      return net::LOAD_FROM_CACHE_IF_OFFLINE;
+    case ROUTE_ONLINE:
+      return 0;
+    case ROUTE_OFFLINE:
+      return net::LOAD_ONLY_FROM_CACHE;
+  }
+  NOTREACHED();
+  return 0;
+}
+
+void OfflinePolicy::RequestCompleted(
+    int child_id, int route_id, const net::HttpResponseInfo& response_info) {
+  // Don't do anything if offline mode is disabled.
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableOfflineCacheAccess))
+    return;
+
+  const RouteMap::iterator it(
+      offline_state_map_.find(std::make_pair(child_id, route_id)));
+
+  // We should have seen this on the incoming side.
+  DCHECK(offline_state_map_.end() != it);
+
+  if (it->second == ROUTE_INIT) {
+    if (response_info.server_data_unavailable) {
+      it->second = ROUTE_OFFLINE;
+    } else if (response_info.network_verified) {
+      // If we got the response from the network or validated it as part
+      // of this request, that means our connection to the host is working.
+      it->second = ROUTE_ONLINE;
+    }
+  }
+}
+
+void OfflinePolicy::RouteRemoved(int child_id, int route_id) {
+  // Don't do anything if offline mode is disabled.
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableOfflineCacheAccess))
+    return;
+
+  const RouteMap::iterator it(
+      offline_state_map_.find(std::make_pair(child_id, route_id)));
+  if (offline_state_map_.end() != it)
+    offline_state_map_.erase(it);
+}
+
+}  // namespace content