path: root/chrome/browser/renderer_host/resource_dispatcher_host.cc

// Copyright (c) 2010 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.

// See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading

#include "chrome/browser/renderer_host/resource_dispatcher_host.h"

#include <vector>

#include "base/logging.h"
#include "base/command_line.h"
#include "base/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/scoped_ptr.h"
#include "base/shared_memory.h"
#include "base/stl_util-inl.h"
#include "base/time.h"
#include "chrome/browser/cert_store.h"
#include "chrome/browser/child_process_security_policy.h"
#include "chrome/browser/chrome_blob_storage_context.h"
#include "chrome/browser/cross_site_request_manager.h"
#include "chrome/browser/download/download_file_manager.h"
#include "chrome/browser/download/download_manager.h"
#include "chrome/browser/download/download_request_limiter.h"
#include "chrome/browser/download/save_file_manager.h"
#include "chrome/browser/extensions/user_script_listener.h"
#include "chrome/browser/external_protocol_handler.h"
#include "chrome/browser/in_process_webkit/webkit_thread.h"
#include "chrome/browser/login_prompt.h"
#include "chrome/browser/net/chrome_url_request_context.h"
#include "chrome/browser/net/url_request_tracking.h"
#include "chrome/browser/plugin_service.h"
#include "chrome/browser/profile.h"
#include "chrome/browser/renderer_host/async_resource_handler.h"
#include "chrome/browser/renderer_host/buffered_resource_handler.h"
#include "chrome/browser/renderer_host/cross_site_resource_handler.h"
#include "chrome/browser/renderer_host/download_resource_handler.h"
#include "chrome/browser/renderer_host/global_request_id.h"
#include "chrome/browser/renderer_host/redirect_to_file_resource_handler.h"
#include "chrome/browser/renderer_host/render_view_host.h"
#include "chrome/browser/renderer_host/render_view_host_delegate.h"
#include "chrome/browser/renderer_host/render_view_host_notification_task.h"
#include "chrome/browser/renderer_host/resource_dispatcher_host_request_info.h"
#include "chrome/browser/renderer_host/resource_queue.h"
#include "chrome/browser/renderer_host/resource_request_details.h"
#include "chrome/browser/renderer_host/safe_browsing_resource_handler.h"
#include "chrome/browser/renderer_host/save_file_resource_handler.h"
#include "chrome/browser/renderer_host/socket_stream_dispatcher_host.h"
#include "chrome/browser/renderer_host/sync_resource_handler.h"
#include "chrome/browser/safe_browsing/safe_browsing_service.h"
#include "chrome/browser/ssl/ssl_client_auth_handler.h"
#include "chrome/browser/ssl/ssl_manager.h"
#include "chrome/browser/worker_host/worker_service.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/notification_service.h"
#include "chrome/common/render_messages.h"
#include "chrome/common/render_messages_params.h"
#include "chrome/common/url_constants.h"
#include "net/base/auth.h"
#include "net/base/cert_status_flags.h"
#include "net/base/load_flags.h"
#include "net/base/mime_util.h"
#include "net/base/net_errors.h"
#include "net/base/request_priority.h"
#include "net/base/ssl_cert_request_info.h"
#include "net/base/upload_data.h"
#include "net/http/http_response_headers.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_context.h"
#include "webkit/appcache/appcache_interceptor.h"
#include "webkit/appcache/appcache_interfaces.h"
#include "webkit/blob/blob_storage_controller.h"
#include "webkit/blob/deletable_file_reference.h"

// TODO(oshima): Enable this for other platforms.
#if defined(OS_CHROMEOS)
#include "chrome/browser/renderer_host/offline_resource_handler.h"
#endif

using base::Time;
using base::TimeDelta;
using base::TimeTicks;
using webkit_blob::DeletableFileReference;

// ----------------------------------------------------------------------------

// A ShutdownTask proxies a shutdown task from the UI thread to the IO thread.
// It should be constructed on the UI thread and run in the IO thread.
class ResourceDispatcherHost::ShutdownTask : public Task {
 public:
  explicit ShutdownTask(ResourceDispatcherHost* resource_dispatcher_host)
      : rdh_(resource_dispatcher_host) {
  }

  void Run() {
    rdh_->OnShutdown();
  }

 private:
  ResourceDispatcherHost* rdh_;
};

namespace {

// The interval for calls to ResourceDispatcherHost::UpdateLoadStates
const int kUpdateLoadStatesIntervalMsec = 100;

// Maximum number of pending data messages sent to the renderer at any
// given time for a given request.
const int kMaxPendingDataMessages = 20;

// Maximum byte "cost" of all the outstanding requests for a renderer.
// See delcaration of |max_outstanding_requests_cost_per_process_| for details.
// This bound is 25MB, which allows for around 6000 outstanding requests.
const int kMaxOutstandingRequestsCostPerProcess = 26214400;

// Consults the RendererSecurity policy to determine whether the
// ResourceDispatcherHost should service this request.  A request might be
// disallowed if the renderer is not authorized to retrieve the request URL or
// if the renderer is attempting to upload an unauthorized file.
bool ShouldServiceRequest(ChildProcessInfo::ProcessType process_type,
                          int child_id,
                          const ViewHostMsg_Resource_Request& request_data)  {
  if (process_type == ChildProcessInfo::PLUGIN_PROCESS)
    return true;

  if (request_data.resource_type == ResourceType::PREFETCH &&
      !ResourceDispatcherHost::is_prefetch_enabled())
    return false;

  ChildProcessSecurityPolicy* policy =
      ChildProcessSecurityPolicy::GetInstance();

  // Check if the renderer is permitted to request the requested URL.
  if (!policy->CanRequestURL(child_id, request_data.url)) {
    VLOG(1) << "Denied unauthorized request for "
            << request_data.url.possibly_invalid_spec();
    return false;
  }

  // Check if the renderer is permitted to upload the requested files.
  if (request_data.upload_data) {
    const std::vector<net::UploadData::Element>* uploads =
        request_data.upload_data->elements();
    std::vector<net::UploadData::Element>::const_iterator iter;
    for (iter = uploads->begin(); iter != uploads->end(); ++iter) {
      if (iter->type() == net::UploadData::TYPE_FILE &&
          !policy->CanReadFile(child_id, iter->file_path())) {
        NOTREACHED() << "Denied unauthorized upload of "
                     << iter->file_path().value();
        return false;
      }
    }
  }

  return true;
}

void PopulateResourceResponse(URLRequest* request,
                              bool replace_extension_localization_templates,
                              ResourceResponse* response) {
  response->response_head.status = request->status();
  response->response_head.request_time = request->request_time();
  response->response_head.response_time = request->response_time();
  response->response_head.headers = request->response_headers();
  request->GetCharset(&response->response_head.charset);
  response->response_head.replace_extension_localization_templates =
      replace_extension_localization_templates;
  response->response_head.content_length = request->GetExpectedContentSize();
  request->GetMimeType(&response->response_head.mime_type);
  response->response_head.was_fetched_via_spdy =
      request->was_fetched_via_spdy();
  response->response_head.was_npn_negotiated = request->was_npn_negotiated();
  response->response_head.was_alternate_protocol_available =
      request->was_alternate_protocol_available();
  response->response_head.was_fetched_via_proxy =
      request->was_fetched_via_proxy();
  appcache::AppCacheInterceptor::GetExtraResponseInfo(
      request,
      &response->response_head.appcache_id,
      &response->response_head.appcache_manifest_url);
}

// Returns a list of all the possible error codes from the network module.
// Note that the error codes are all positive (since histograms expect positive
// sample values).
std::vector<int> GetAllNetErrorCodes() {
  std::vector<int> all_error_codes;
#define NET_ERROR(label, value) all_error_codes.push_back(-(value));
#include "net/base/net_error_list.h"
#undef NET_ERROR
  return all_error_codes;
}

}  // namespace

ResourceDispatcherHost::Receiver::Receiver(ChildProcessInfo::ProcessType type,
                                           int child_id)
    : ChildProcessInfo(type, child_id) {
}

ResourceDispatcherHost::Receiver::~Receiver() {
}

ResourceDispatcherHost::ResourceDispatcherHost()
    : ALLOW_THIS_IN_INITIALIZER_LIST(
          download_file_manager_(new DownloadFileManager(this))),
      download_request_limiter_(new DownloadRequestLimiter()),
      ALLOW_THIS_IN_INITIALIZER_LIST(
          save_file_manager_(new SaveFileManager(this))),
      user_script_listener_(new UserScriptListener(&resource_queue_)),
      safe_browsing_(SafeBrowsingService::CreateSafeBrowsingService()),
      socket_stream_dispatcher_host_(new SocketStreamDispatcherHost),
      webkit_thread_(new WebKitThread),
      request_id_(-1),
      ALLOW_THIS_IN_INITIALIZER_LIST(method_runner_(this)),
      is_shutdown_(false),
      max_outstanding_requests_cost_per_process_(
          kMaxOutstandingRequestsCostPerProcess),
      receiver_(NULL) {
  ResourceQueue::DelegateSet resource_queue_delegates;
  resource_queue_delegates.insert(user_script_listener_.get());
  resource_queue_.Initialize(resource_queue_delegates);
}

ResourceDispatcherHost::~ResourceDispatcherHost() {
  AsyncResourceHandler::GlobalCleanup();
  STLDeleteValues(&pending_requests_);

  user_script_listener_->ShutdownMainThread();
}

void ResourceDispatcherHost::Initialize() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  webkit_thread_->Initialize();
  safe_browsing_->Initialize();
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      NewRunnableFunction(&appcache::AppCacheInterceptor::EnsureRegistered));
}

void ResourceDispatcherHost::Shutdown() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE, new ShutdownTask(this));
}

void ResourceDispatcherHost::SetRequestInfo(
    URLRequest* request,
    ResourceDispatcherHostRequestInfo* info) {
  request->SetUserData(NULL, info);
}

void ResourceDispatcherHost::OnShutdown() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  is_shutdown_ = true;
  resource_queue_.Shutdown();
  STLDeleteValues(&pending_requests_);
  // Make sure we shutdown the timer now, otherwise by the time our destructor
  // runs if the timer is still running the Task is deleted twice (once by
  // the MessageLoop and the second time by RepeatingTimer).
  update_load_states_timer_.Stop();

  // Clear blocked requests if any left.
  // Note that we have to do this in 2 passes as we cannot call
  // CancelBlockedRequestsForRoute while iterating over
  // blocked_requests_map_, as it modifies it.
  std::set<ProcessRouteIDs> ids;
  for (BlockedRequestMap::const_iterator iter = blocked_requests_map_.begin();
       iter != blocked_requests_map_.end(); ++iter) {
    std::pair<std::set<ProcessRouteIDs>::iterator, bool> result =
        ids.insert(iter->first);
    // We should not have duplicates.
    DCHECK(result.second);
  }
  for (std::set<ProcessRouteIDs>::const_iterator iter = ids.begin();
       iter != ids.end(); ++iter) {
    CancelBlockedRequestsForRoute(iter->first, iter->second);
  }
}

bool ResourceDispatcherHost::HandleExternalProtocol(int request_id,
                                                    int child_id,
                                                    int route_id,
                                                    const GURL& url,
                                                    ResourceType::Type type,
                                                    ResourceHandler* handler) {
  if (!ResourceType::IsFrame(type) || URLRequest::IsHandledURL(url))
    return false;

  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      NewRunnableFunction(
          &ExternalProtocolHandler::LaunchUrl, url, child_id, route_id));

  handler->OnResponseCompleted(request_id, URLRequestStatus(
                                               URLRequestStatus::FAILED,
                                               net::ERR_ABORTED),
                               std::string());  // No security info necessary.
  return true;
}

bool ResourceDispatcherHost::OnMessageReceived(const IPC::Message& message,
                                               Receiver* receiver,
                                               bool* message_was_ok) {
  if (!IsResourceDispatcherHostMessage(message)) {
    return socket_stream_dispatcher_host_->OnMessageReceived(
        message, receiver, message_was_ok);
  }

  *message_was_ok = true;
  receiver_ = receiver;

  IPC_BEGIN_MESSAGE_MAP_EX(ResourceDispatcherHost, message, *message_was_ok)
    IPC_MESSAGE_HANDLER(ViewHostMsg_RequestResource, OnRequestResource)
    IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_SyncLoad, OnSyncLoad)
    IPC_MESSAGE_HANDLER(ViewHostMsg_ReleaseDownloadedFile,
                        OnReleaseDownloadedFile)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DataReceived_ACK, OnDataReceivedACK)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DataDownloaded_ACK, OnDataDownloadedACK)
    IPC_MESSAGE_HANDLER(ViewHostMsg_UploadProgress_ACK, OnUploadProgressACK)
    IPC_MESSAGE_HANDLER(ViewHostMsg_CancelRequest, OnCancelRequest)
    IPC_MESSAGE_HANDLER(ViewHostMsg_FollowRedirect, OnFollowRedirect)
    IPC_MESSAGE_HANDLER(ViewHostMsg_ClosePage_ACK, OnClosePageACK)
  IPC_END_MESSAGE_MAP_EX()

  receiver_ = NULL;

  return true;
}

void ResourceDispatcherHost::OnRequestResource(
    const IPC::Message& message,
    int request_id,
    const ViewHostMsg_Resource_Request& request_data) {
  BeginRequest(request_id, request_data, NULL, message.routing_id());
}

// Begins a resource request with the given params on behalf of the specified
// child process.  Responses will be dispatched through the given receiver. The
// process ID is used to lookup TabContents from routing_id's in the case of a
// request from a renderer.  request_context is the cookie/cache context to be
// used for this request.
//
// If sync_result is non-null, then a SyncLoad reply will be generated, else
// a normal asynchronous set of response messages will be generated.
void ResourceDispatcherHost::OnSyncLoad(
    int request_id,
    const ViewHostMsg_Resource_Request& request_data,
    IPC::Message* sync_result) {
  BeginRequest(request_id, request_data, sync_result,
               sync_result->routing_id());
}

void ResourceDispatcherHost::BeginRequest(
    int request_id,
    const ViewHostMsg_Resource_Request& request_data,
    IPC::Message* sync_result,  // only valid for sync
    int route_id) {
  ChildProcessInfo::ProcessType process_type = receiver_->type();
  int child_id = receiver_->id();
  ChromeURLRequestContext* context = static_cast<ChromeURLRequestContext*>(
      receiver_->GetRequestContext(request_id, request_data));
  if (!context) {
    URLRequestContextGetter* context_getter =
        Profile::GetDefaultRequestContext();
    if (context_getter) {
      context = static_cast<ChromeURLRequestContext*>(
          context_getter->GetURLRequestContext());
    }
  }

  // Might need to resolve the blob references in the upload data.
  if (request_data.upload_data && context) {
    context->blob_storage_context()->controller()->
        ResolveBlobReferencesInUploadData(request_data.upload_data.get());
  }

  if (is_shutdown_ ||
      !ShouldServiceRequest(process_type, child_id, request_data)) {
    URLRequestStatus status(URLRequestStatus::FAILED, net::ERR_ABORTED);
    if (sync_result) {
      SyncLoadResult result;
      result.status = status;
      ViewHostMsg_SyncLoad::WriteReplyParams(sync_result, result);
      receiver_->Send(sync_result);
    } else {
      // Tell the renderer that this request was disallowed.
      receiver_->Send(new ViewMsg_Resource_RequestComplete(
          route_id,
          request_id,
          status,
          std::string(),   // No security info needed, connection was not
          base::Time()));  // established.
    }
    return;
  }

  // Ensure the Chrome plugins are loaded, as they may intercept network
  // requests.  Does nothing if they are already loaded.
  // TODO(mpcomplete): This takes 200 ms!  Investigate parallelizing this by
  // starting the load earlier in a BG thread.
  PluginService::GetInstance()->LoadChromePlugins(this);

  // Construct the event handler.
  scoped_refptr<ResourceHandler> handler;
  if (sync_result) {
    handler = new SyncResourceHandler(receiver_,
                                      child_id,
                                      request_data.url,
                                      sync_result,
                                      this);
  } else {
    handler = new AsyncResourceHandler(receiver_,
                                       child_id,
                                       route_id,
                                       receiver_->handle(),
                                       request_data.url,
                                       this);
  }

  // The RedirectToFileResourceHandler depends on being next in the chain.
  if (request_data.download_to_file)
    handler = new RedirectToFileResourceHandler(handler, child_id, this);

  if (HandleExternalProtocol(request_id, child_id, route_id,
                             request_data.url, request_data.resource_type,
                             handler)) {
    return;
  }

  // Construct the request.
  URLRequest* request = new URLRequest(request_data.url, this);
  request->set_method(request_data.method);
  request->set_first_party_for_cookies(request_data.first_party_for_cookies);
  request->set_referrer(CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kNoReferrers) ? std::string() : request_data.referrer.spec());
  net::HttpRequestHeaders headers;
  headers.AddHeadersFromString(request_data.headers);
  request->SetExtraRequestHeaders(headers);

  int load_flags = request_data.load_flags;
  // Although EV status is irrelevant to sub-frames and sub-resources, we have
  // to perform EV certificate verification on all resources because an HTTP
  // keep-alive connection created to load a sub-frame or a sub-resource could
  // be reused to load a main frame.
  load_flags |= net::LOAD_VERIFY_EV_CERT;
  if (request_data.resource_type == ResourceType::MAIN_FRAME) {
    load_flags |= net::LOAD_MAIN_FRAME;
  } else if (request_data.resource_type == ResourceType::SUB_FRAME) {
    load_flags |= net::LOAD_SUB_FRAME;
  } else if (request_data.resource_type == ResourceType::PREFETCH) {
    load_flags |= net::LOAD_PREFETCH;
  }
  // Raw headers are sensitive, as they inclide Cookie/Set-Cookie, so only
  // allow requesting them if requestor has ReadRawCookies permission.
  if ((load_flags & net::LOAD_REPORT_RAW_HEADERS)
      && !ChildProcessSecurityPolicy::GetInstance()->
              CanReadRawCookies(child_id)) {
    VLOG(1) << "Denied unathorized request for raw headers";
    load_flags &= ~net::LOAD_REPORT_RAW_HEADERS;
  }

  request->set_load_flags(load_flags);
  request->set_context(context);
  request->set_priority(DetermineRequestPriority(request_data.resource_type));

  // Set upload data.
  uint64 upload_size = 0;
  if (request_data.upload_data) {
    request->set_upload(request_data.upload_data);
    upload_size = request_data.upload_data->GetContentLength();
  }

  // Install a CrossSiteResourceHandler if this request is coming from a
  // RenderViewHost with a pending cross-site request.  We only check this for
  // MAIN_FRAME requests. Unblock requests only come from a blocked page, do
  // not count as cross-site, otherwise it gets blocked indefinitely.
  if (request_data.resource_type == ResourceType::MAIN_FRAME &&
      process_type == ChildProcessInfo::RENDER_PROCESS &&
      Singleton<CrossSiteRequestManager>::get()->
          HasPendingCrossSiteRequest(child_id, route_id)) {
    // Wrap the event handler to be sure the current page's onunload handler
    // has a chance to run before we render the new page.
    handler = new CrossSiteResourceHandler(handler,
                                           child_id,
                                           route_id,
                                           this);
  }

  // Insert a buffered event handler before the actual one.
  handler = new BufferedResourceHandler(handler, this, request);

  // Insert safe browsing at the front of the chain, so it gets to decide
  // on policies first.
  if (safe_browsing_->enabled()) {
    handler = CreateSafeBrowsingResourceHandler(handler, child_id, route_id,
                                                request_data.resource_type);
  }

#if defined(OS_CHROMEOS)
  // We check offline first, then check safe browsing so that we still can block
  // unsafe site after we remove offline page.
  handler =
      new OfflineResourceHandler(handler, child_id, route_id, this, request);
#endif

  // Make extra info and read footer (contains request ID).
  ResourceDispatcherHostRequestInfo* extra_info =
      new ResourceDispatcherHostRequestInfo(
          handler,
          process_type,
          child_id,
          route_id,
          request_id,
          request_data.frame_origin,
          request_data.main_frame_origin,
          request_data.resource_type,
          upload_size,
          false,  // is download
          ResourceType::IsFrame(request_data.resource_type), // allow_download
          request_data.host_renderer_id,
          request_data.host_render_view_id);
  ApplyExtensionLocalizationFilter(request_data.url, request_data.resource_type,
                                   extra_info);
  SetRequestInfo(request, extra_info);  // Request takes ownership.
  chrome_browser_net::SetOriginProcessUniqueIDForRequest(
      request_data.origin_child_id, request);

  if (request->url().SchemeIs(chrome::kBlobScheme) && context) {
    // Hang on to a reference to ensure the blob is not released prior
    // to the job being started.
    webkit_blob::BlobStorageController* controller =
        context->blob_storage_context()->controller();
    extra_info->set_requested_blob_data(
        controller->GetBlobDataFromUrl(request->url()));
  }

  // Have the appcache associate its extra info with the request.
  appcache::AppCacheInterceptor::SetExtraRequestInfo(
      request, context ? context->appcache_service() : NULL, child_id,
      request_data.appcache_host_id, request_data.resource_type);

  BeginRequestInternal(request);
}

void ResourceDispatcherHost::OnReleaseDownloadedFile(int request_id) {
  DCHECK(pending_requests_.end() ==
         pending_requests_.find(GlobalRequestID(receiver_->id(), request_id)));
  UnregisterDownloadedTempFile(receiver_->id(), request_id);
}

void ResourceDispatcherHost::OnDataReceivedACK(int request_id) {
  DataReceivedACK(receiver_->id(), request_id);
}

void ResourceDispatcherHost::DataReceivedACK(int child_id,
                                             int request_id) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end())
    return;

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);

  // Decrement the number of pending data messages.
  info->DecrementPendingDataCount();

  // If the pending data count was higher than the max, resume the request.
  if (info->pending_data_count() == kMaxPendingDataMessages) {
    // Decrement the pending data count one more time because we also
    // incremented it before pausing the request.
    info->DecrementPendingDataCount();

    // Resume the request.
    PauseRequest(child_id, request_id, false);
  }
}

void ResourceDispatcherHost::OnDataDownloadedACK(int request_id) {
  // TODO(michaeln): maybe throttle DataDownloaded messages
}

void ResourceDispatcherHost::RegisterDownloadedTempFile(
    int receiver_id, int request_id, DeletableFileReference* reference) {
  // Note: receiver_id is the child_id is the render_process_id...
  registered_temp_files_[receiver_id][request_id] = reference;
  ChildProcessSecurityPolicy::GetInstance()->GrantReadFile(
      receiver_id, reference->path());
}

void ResourceDispatcherHost::UnregisterDownloadedTempFile(
    int receiver_id, int request_id) {
  DeletableFilesMap& map = registered_temp_files_[receiver_id];
  DeletableFilesMap::iterator found = map.find(request_id);
  if (found == map.end())
    return;

  ChildProcessSecurityPolicy::GetInstance()->RevokeAllPermissionsForFile(
      receiver_id, found->second->path());
  map.erase(found);
}

bool ResourceDispatcherHost::Send(IPC::Message* message) {
  delete message;
  return false;
}

void ResourceDispatcherHost::OnUploadProgressACK(int request_id) {
  int child_id = receiver_->id();
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end())
    return;

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);
  info->set_waiting_for_upload_progress_ack(false);
}

void ResourceDispatcherHost::OnCancelRequest(int request_id) {
  CancelRequest(receiver_->id(), request_id, true);
}

void ResourceDispatcherHost::OnFollowRedirect(
    int request_id,
    bool has_new_first_party_for_cookies,
    const GURL& new_first_party_for_cookies) {
  FollowDeferredRedirect(receiver_->id(), request_id,
                         has_new_first_party_for_cookies,
                         new_first_party_for_cookies);
}

ResourceHandler* ResourceDispatcherHost::CreateSafeBrowsingResourceHandler(
    ResourceHandler* handler, int child_id, int route_id,
    ResourceType::Type resource_type) {
  return new SafeBrowsingResourceHandler(handler,
                                         child_id,
                                         route_id,
                                         resource_type,
                                         safe_browsing_,
                                         this,
                                         receiver_);
}

ResourceDispatcherHostRequestInfo*
ResourceDispatcherHost::CreateRequestInfoForBrowserRequest(
    ResourceHandler* handler, int child_id, int route_id, bool download) {
  return new ResourceDispatcherHostRequestInfo(handler,
                                               ChildProcessInfo::RENDER_PROCESS,
                                               child_id,
                                               route_id,
                                               request_id_,
                                               "null",  // frame_origin
                                               "null",  // main_frame_origin
                                               ResourceType::SUB_RESOURCE,
                                               0,  // upload_size
                                               download,  // is_download
                                               download,  // allow_download
                                               -1,  // Host renderer id
                                               -1);  // Host render view id
}

void ResourceDispatcherHost::OnClosePageACK(
    const ViewMsg_ClosePage_Params& params) {
  if (params.for_cross_site_transition) {
    // Closes for cross-site transitions are handled such that the cross-site
    // transition continues.
    GlobalRequestID global_id(params.new_render_process_host_id,
                              params.new_request_id);
    PendingRequestList::iterator i = pending_requests_.find(global_id);
    if (i != pending_requests_.end()) {
      // The response we were meant to resume could have already been canceled.
      ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);
      if (info->cross_site_handler())
        info->cross_site_handler()->ResumeResponse();
    }
  } else {
    // This is a tab close, so just forward the message to close it.
    DCHECK(params.new_render_process_host_id == -1);
    DCHECK(params.new_request_id == -1);
    CallRenderViewHost(params.closing_process_id,
                       params.closing_route_id,
                       &RenderViewHost::ClosePageIgnoringUnloadEvents);
  }
}

// We are explicitly forcing the download of 'url'.
void ResourceDispatcherHost::BeginDownload(
    const GURL& url,
    const GURL& referrer,
    const DownloadSaveInfo& save_info,
    bool prompt_for_save_location,
    int child_id,
    int route_id,
    URLRequestContext* request_context) {
  if (is_shutdown_)
    return;

  // Check if the renderer is permitted to request the requested URL.
  if (!ChildProcessSecurityPolicy::GetInstance()->
          CanRequestURL(child_id, url)) {
    VLOG(1) << "Denied unauthorized download request for "
            << url.possibly_invalid_spec();
    return;
  }

  // Ensure the Chrome plugins are loaded, as they may intercept network
  // requests.  Does nothing if they are already loaded.
  PluginService::GetInstance()->LoadChromePlugins(this);
  URLRequest* request = new URLRequest(url, this);

  request_id_--;

  scoped_refptr<ResourceHandler> handler(
      new DownloadResourceHandler(this,
                                  child_id,
                                  route_id,
                                  request_id_,
                                  url,
                                  download_file_manager_.get(),
                                  request,
                                  prompt_for_save_location,
                                  save_info));

  if (safe_browsing_->enabled()) {
    handler = CreateSafeBrowsingResourceHandler(handler, child_id, route_id,
                                                ResourceType::MAIN_FRAME);
  }

  if (!URLRequest::IsHandledURL(url)) {
    VLOG(1) << "Download request for unsupported protocol: "
            << url.possibly_invalid_spec();
    return;
  }

  request->set_method("GET");
  request->set_referrer(CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kNoReferrers) ? std::string() : referrer.spec());
  request->set_context(request_context);
  request->set_load_flags(request->load_flags() |
      net::LOAD_IS_DOWNLOAD);

  ResourceDispatcherHostRequestInfo* extra_info =
      CreateRequestInfoForBrowserRequest(handler, child_id, route_id, true);
  SetRequestInfo(request, extra_info);  // Request takes ownership.
  chrome_browser_net::SetOriginProcessUniqueIDForRequest(child_id, request);

  BeginRequestInternal(request);
}

// This function is only used for saving feature.
void ResourceDispatcherHost::BeginSaveFile(const GURL& url,
                                           const GURL& referrer,
                                           int child_id,
                                           int route_id,
                                           URLRequestContext* request_context) {
  if (is_shutdown_)
    return;

  // Ensure the Chrome plugins are loaded, as they may intercept network
  // requests.  Does nothing if they are already loaded.
  PluginService::GetInstance()->LoadChromePlugins(this);

  scoped_refptr<ResourceHandler> handler(
      new SaveFileResourceHandler(child_id,
                                  route_id,
                                  url,
                                  save_file_manager_.get()));
  request_id_--;

  bool known_proto = URLRequest::IsHandledURL(url);
  if (!known_proto) {
    // Since any URLs which have non-standard scheme have been filtered
    // by save manager(see GURL::SchemeIsStandard). This situation
    // should not happen.
    NOTREACHED();
    return;
  }

  URLRequest* request = new URLRequest(url, this);
  request->set_method("GET");
  request->set_referrer(CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kNoReferrers) ? std::string() : referrer.spec());
  // So far, for saving page, we need fetch content from cache, in the
  // future, maybe we can use a configuration to configure this behavior.
  request->set_load_flags(net::LOAD_PREFERRING_CACHE);
  request->set_context(request_context);

  // Since we're just saving some resources we need, disallow downloading.
  ResourceDispatcherHostRequestInfo* extra_info =
      CreateRequestInfoForBrowserRequest(handler, child_id, route_id, false);
  SetRequestInfo(request, extra_info);  // Request takes ownership.
  chrome_browser_net::SetOriginProcessUniqueIDForRequest(child_id, request);

  BeginRequestInternal(request);
}

void ResourceDispatcherHost::FollowDeferredRedirect(
    int child_id,
    int request_id,
    bool has_new_first_party_for_cookies,
    const GURL& new_first_party_for_cookies) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end() || !i->second->status().is_success()) {
    DLOG(WARNING) << "FollowDeferredRedirect for invalid request";
    return;
  }

  if (has_new_first_party_for_cookies)
    i->second->set_first_party_for_cookies(new_first_party_for_cookies);
  i->second->FollowDeferredRedirect();
}

void ResourceDispatcherHost::StartDeferredRequest(int process_unique_id,
                                                  int request_id) {
  GlobalRequestID global_id(process_unique_id, request_id);
  PendingRequestList::iterator i = pending_requests_.find(global_id);
  if (i == pending_requests_.end()) {
    // The request may have been destroyed
    LOG(WARNING) << "Trying to resume a non-existent request ("
                 << process_unique_id << ", " << request_id << ")";
    return;
  }

  // TODO(eroman): are there other considerations for paused or blocked
  //               requests?

  URLRequest* request = i->second;
  InsertIntoResourceQueue(request, *InfoForRequest(request));
}

bool ResourceDispatcherHost::WillSendData(int child_id,
                                          int request_id) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end()) {
    NOTREACHED() << "WillSendData for invalid request";
    return false;
  }

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);

  info->IncrementPendingDataCount();
  if (info->pending_data_count() > kMaxPendingDataMessages) {
    // We reached the max number of data messages that can be sent to
    // the renderer for a given request. Pause the request and wait for
    // the renderer to start processing them before resuming it.
    PauseRequest(child_id, request_id, true);
    return false;
  }

  return true;
}

void ResourceDispatcherHost::PauseRequest(int child_id,
                                          int request_id,
                                          bool pause) {
  GlobalRequestID global_id(child_id, request_id);
  PendingRequestList::iterator i = pending_requests_.find(global_id);
  if (i == pending_requests_.end()) {
    DLOG(WARNING) << "Pausing a request that wasn't found";
    return;
  }

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);
  int pause_count = info->pause_count() + (pause ? 1 : -1);
  if (pause_count < 0) {
    NOTREACHED();  // Unbalanced call to pause.
    return;
  }
  info->set_pause_count(pause_count);

  VLOG(1) << "To pause (" << pause << "): " << i->second->url().spec();

  // If we're resuming, kick the request to start reading again. Run the read
  // asynchronously to avoid recursion problems.
  if (info->pause_count() == 0) {
    MessageLoop::current()->PostTask(FROM_HERE,
        method_runner_.NewRunnableMethod(
            &ResourceDispatcherHost::ResumeRequest, global_id));
  }
}

int ResourceDispatcherHost::GetOutstandingRequestsMemoryCost(
    int child_id) const {
  OutstandingRequestsMemoryCostMap::const_iterator entry =
      outstanding_requests_memory_cost_map_.find(child_id);
  return (entry == outstanding_requests_memory_cost_map_.end()) ?
      0 : entry->second;
}

// The object died, so cancel and detach all requests associated with it except
// for downloads, which belong to the browser process even if initiated via a
// renderer.
void ResourceDispatcherHost::CancelRequestsForProcess(int child_id) {
  socket_stream_dispatcher_host_->CancelRequestsForProcess(child_id);
  CancelRequestsForRoute(child_id, -1 /* cancel all */);
  registered_temp_files_.erase(child_id);
}

void ResourceDispatcherHost::CancelRequestsForRoute(int child_id,
                                                    int route_id) {
  // Since pending_requests_ is a map, we first build up a list of all of the
  // matching requests to be cancelled, and then we cancel them.  Since there
  // may be more than one request to cancel, we cannot simply hold onto the map
  // iterators found in the first loop.

  // Find the global ID of all matching elements.
  std::vector<GlobalRequestID> matching_requests;
  for (PendingRequestList::const_iterator i = pending_requests_.begin();
       i != pending_requests_.end(); ++i) {
    if (i->first.child_id == child_id) {
      ResourceDispatcherHostRequestInfo* info = InfoForRequest(i->second);
      if (!info->is_download() &&
          (route_id == -1 || route_id == info->route_id())) {
        matching_requests.push_back(
            GlobalRequestID(child_id, i->first.request_id));
      }
    }
  }

  // Remove matches.
  for (size_t i = 0; i < matching_requests.size(); ++i) {
    PendingRequestList::iterator iter =
        pending_requests_.find(matching_requests[i]);
    // Although every matching request was in pending_requests_ when we built
    // matching_requests, it is normal for a matching request to be not found
    // in pending_requests_ after we have removed some matching requests from
    // pending_requests_.  For example, deleting a URLRequest that has
    // exclusive (write) access to an HTTP cache entry may unblock another
    // URLRequest that needs exclusive access to the same cache entry, and
    // that URLRequest may complete and remove itself from pending_requests_.
    // So we need to check that iter is not equal to pending_requests_.end().
    if (iter != pending_requests_.end())
      RemovePendingRequest(iter);
  }

  // Now deal with blocked requests if any.
  if (route_id != -1) {
    if (blocked_requests_map_.find(std::pair<int, int>(child_id, route_id)) !=
        blocked_requests_map_.end()) {
      CancelBlockedRequestsForRoute(child_id, route_id);
    }
  } else {
    // We have to do all render views for the process |child_id|.
    // Note that we have to do this in 2 passes as we cannot call
    // CancelBlockedRequestsForRoute while iterating over
    // blocked_requests_map_, as it modifies it.
    std::set<int> route_ids;
    for (BlockedRequestMap::const_iterator iter = blocked_requests_map_.begin();
         iter != blocked_requests_map_.end(); ++iter) {
      if (iter->first.first == child_id)
        route_ids.insert(iter->first.second);
    }
    for (std::set<int>::const_iterator iter = route_ids.begin();
        iter != route_ids.end(); ++iter) {
      CancelBlockedRequestsForRoute(child_id, *iter);
    }
  }
}

// Cancels the request and removes it from the list.
void ResourceDispatcherHost::RemovePendingRequest(int child_id,
                                                  int request_id) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end()) {
    NOTREACHED() << "Trying to remove a request that's not here";
    return;
  }
  RemovePendingRequest(i);
}

void ResourceDispatcherHost::RemovePendingRequest(
    const PendingRequestList::iterator& iter) {
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(iter->second);

  // Remove the memory credit that we added when pushing the request onto
  // the pending list.
  IncrementOutstandingRequestsMemoryCost(-1 * info->memory_cost(),
                                         info->child_id());

  // Notify interested parties that the request object is going away.
  if (info->login_handler())
    info->login_handler()->OnRequestCancelled();
  if (info->ssl_client_auth_handler())
    info->ssl_client_auth_handler()->OnRequestCancelled();
  resource_queue_.RemoveRequest(iter->first);

  delete iter->second;
  pending_requests_.erase(iter);

  // If we have no more pending requests, then stop the load state monitor
  if (pending_requests_.empty())
    update_load_states_timer_.Stop();
}

// URLRequest::Delegate -------------------------------------------------------

void ResourceDispatcherHost::OnReceivedRedirect(URLRequest* request,
                                                const GURL& new_url,
                                                bool* defer_redirect) {
  VLOG(1) << "OnReceivedRedirect: " << request->url().spec();
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

  DCHECK(request->status().is_success());

  if (info->process_type() != ChildProcessInfo::PLUGIN_PROCESS &&
      !ChildProcessSecurityPolicy::GetInstance()->
          CanRequestURL(info->child_id(), new_url)) {
    VLOG(1) << "Denied unauthorized request for "
            << new_url.possibly_invalid_spec();

    // Tell the renderer that this request was disallowed.
    CancelRequestInternal(request, false);
    return;
  }

  NotifyReceivedRedirect(request, info->child_id(), new_url);

  if (HandleExternalProtocol(info->request_id(), info->child_id(),
                             info->route_id(), new_url,
                             info->resource_type(), info->resource_handler())) {
    // The request is complete so we can remove it.
    RemovePendingRequest(info->child_id(), info->request_id());
    return;
  }

  scoped_refptr<ResourceResponse> response(new ResourceResponse);
  PopulateResourceResponse(request,
      info->replace_extension_localization_templates(), response);
  if (!info->resource_handler()->OnRequestRedirected(info->request_id(),
                                                     new_url,
                                                     response, defer_redirect))
    CancelRequestInternal(request, false);
}

void ResourceDispatcherHost::OnAuthRequired(
    URLRequest* request,
    net::AuthChallengeInfo* auth_info) {
  if (request->load_flags() & net::LOAD_PREFETCH) {
    request->CancelAuth();
    return;
  }
  // Create a login dialog on the UI thread to get authentication data,
  // or pull from cache and continue on the IO thread.
  // TODO(mpcomplete): We should block the parent tab while waiting for
  // authentication.
  // That would also solve the problem of the URLRequest being cancelled
  // before we receive authentication.
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  DCHECK(!info->login_handler()) <<
      "OnAuthRequired called with login_handler pending";
  info->set_login_handler(CreateLoginPrompt(auth_info, request));
}

void ResourceDispatcherHost::OnCertificateRequested(
    URLRequest* request,
    net::SSLCertRequestInfo* cert_request_info) {
  DCHECK(request);

  if (cert_request_info->client_certs.empty()) {
    // No need to query the user if there are no certs to choose from.
    request->ContinueWithCertificate(NULL);
    return;
  }

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  DCHECK(!info->ssl_client_auth_handler()) <<
      "OnCertificateRequested called with ssl_client_auth_handler pending";
  info->set_ssl_client_auth_handler(
      new SSLClientAuthHandler(request, cert_request_info));
  info->ssl_client_auth_handler()->SelectCertificate();
}

void ResourceDispatcherHost::OnSSLCertificateError(
    URLRequest* request,
    int cert_error,
    net::X509Certificate* cert) {
  DCHECK(request);
  SSLManager::OnSSLCertificateError(this, request, cert_error, cert);
}

void ResourceDispatcherHost::OnSetCookie(URLRequest* request,
                                         const std::string& cookie_line,
                                         const net::CookieOptions& options,
                                         bool blocked_by_policy) {
  VLOG(1) << "OnSetCookie: " << request->url().spec();

  int render_process_id, render_view_id;
  if (!RenderViewForRequest(request, &render_process_id, &render_view_id))
    return;

  CallRenderViewHostContentSettingsDelegate(
      render_process_id, render_view_id,
      &RenderViewHostDelegate::ContentSettings::OnCookieAccessed,
      request->url(), cookie_line, options, blocked_by_policy);
}

void ResourceDispatcherHost::OnResponseStarted(URLRequest* request) {
  VLOG(1) << "OnResponseStarted: " << request->url().spec();
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  if (PauseRequestIfNeeded(info)) {
    VLOG(1) << "OnResponseStarted pausing: " << request->url().spec();
    return;
  }

  if (request->status().is_success()) {
    // We want to send a final upload progress message prior to sending
    // the response complete message even if we're waiting for an ack to
    // to a previous upload progress message.
    info->set_waiting_for_upload_progress_ack(false);
    MaybeUpdateUploadProgress(info, request);

    if (!CompleteResponseStarted(request)) {
      CancelRequestInternal(request, false);
    } else {
      // Check if the handler paused the request in their OnResponseStarted.
      if (PauseRequestIfNeeded(info)) {
        VLOG(1) << "OnResponseStarted pausing2: " << request->url().spec();
        return;
      }

      StartReading(request);
    }
  } else {
    OnResponseCompleted(request);
  }
}

bool ResourceDispatcherHost::CompleteResponseStarted(URLRequest* request) {
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

  scoped_refptr<ResourceResponse> response(new ResourceResponse);
  PopulateResourceResponse(request,
      info->replace_extension_localization_templates(), response);

  if (request->ssl_info().cert) {
    int cert_id =
        CertStore::GetSharedInstance()->StoreCert(request->ssl_info().cert,
                                                  info->child_id());
    response->response_head.security_info =
        SSLManager::SerializeSecurityInfo(
            cert_id, request->ssl_info().cert_status,
            request->ssl_info().security_bits,
            request->ssl_info().connection_status);
  } else {
    // We should not have any SSL state.
    DCHECK(!request->ssl_info().cert_status &&
           request->ssl_info().security_bits == -1 &&
           !request->ssl_info().connection_status);
  }

  NotifyResponseStarted(request, info->child_id());
  info->set_called_on_response_started(true);
  return info->resource_handler()->OnResponseStarted(info->request_id(),
                                                     response.get());
}

void ResourceDispatcherHost::CancelRequest(int child_id,
                                           int request_id,
                                           bool from_renderer) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end()) {
    // We probably want to remove this warning eventually, but I wanted to be
    // able to notice when this happens during initial development since it
    // should be rare and may indicate a bug.
    DLOG(WARNING) << "Canceling a request that wasn't found";
    return;
  }
  CancelRequestInternal(i->second, from_renderer);
}

void ResourceDispatcherHost::CancelRequestInternal(URLRequest* request,
                                                   bool from_renderer) {
  VLOG(1) << "CancelRequest: " << request->url().spec();

  // WebKit will send us a cancel for downloads since it no longer handles them.
  // In this case, ignore the cancel since we handle downloads in the browser.
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  if (!from_renderer || !info->is_download()) {
    if (info->login_handler()) {
      info->login_handler()->OnRequestCancelled();
      info->set_login_handler(NULL);
    }
    if (info->ssl_client_auth_handler()) {
      info->ssl_client_auth_handler()->OnRequestCancelled();
      info->set_ssl_client_auth_handler(NULL);
    }
    request->Cancel();
    // Our callers assume |request| is valid after we return.
    DCHECK(IsValidRequest(request));
  }

  // Do not remove from the pending requests, as the request will still
  // call AllDataReceived, and may even have more data before it does
  // that.
}

int ResourceDispatcherHost::IncrementOutstandingRequestsMemoryCost(
    int cost,
    int child_id) {
  // Retrieve the previous value (defaulting to 0 if not found).
  OutstandingRequestsMemoryCostMap::iterator prev_entry =
      outstanding_requests_memory_cost_map_.find(child_id);
  int new_cost = 0;
  if (prev_entry != outstanding_requests_memory_cost_map_.end())
    new_cost = prev_entry->second;

  // Insert/update the total; delete entries when their value reaches 0.
  new_cost += cost;
  CHECK(new_cost >= 0);
  if (new_cost == 0)
    outstanding_requests_memory_cost_map_.erase(prev_entry);
  else
    outstanding_requests_memory_cost_map_[child_id] = new_cost;

  return new_cost;
}

// static
int ResourceDispatcherHost::CalculateApproximateMemoryCost(
    URLRequest* request) {
  // The following fields should be a minor size contribution (experimentally
  // on the order of 100). However since they are variable length, it could
  // in theory be a sizeable contribution.
  int strings_cost = request->extra_request_headers().ToString().size() +
                     request->original_url().spec().size() +
                     request->referrer().size() +
                     request->method().size();

  int upload_cost = 0;

  // TODO(eroman): don't enable the upload throttling until we have data
  // showing what a reasonable limit is (limiting to 25MB of uploads may
  // be too restrictive).
#if 0
  // Sum all the (non-file) upload data attached to the request, if any.
  if (request->has_upload()) {
    const std::vector<net::UploadData::Element>& uploads =
        request->get_upload()->elements();
    std::vector<net::UploadData::Element>::const_iterator iter;
    for (iter = uploads.begin(); iter != uploads.end(); ++iter) {
      if (iter->type() == net::UploadData::TYPE_BYTES) {
        int64 element_size = iter->GetContentLength();
        // This cast should not result in truncation.
        upload_cost += static_cast<int>(element_size);
      }
    }
  }
#endif

  // Note that this expression will typically be dominated by:
  // |kAvgBytesPerOutstandingRequest|.
  return kAvgBytesPerOutstandingRequest + strings_cost + upload_cost;
}

void ResourceDispatcherHost::BeginRequestInternal(URLRequest* request) {
  DCHECK(!request->is_pending());
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

  // Add the memory estimate that starting this request will consume.
  info->set_memory_cost(CalculateApproximateMemoryCost(request));
  int memory_cost = IncrementOutstandingRequestsMemoryCost(info->memory_cost(),
                                                           info->child_id());

  // If enqueing/starting this request will exceed our per-process memory
  // bound, abort it right away.
  if (memory_cost > max_outstanding_requests_cost_per_process_) {
    // We call "SimulateError()" as a way of setting the URLRequest's
    // status -- it has no effect beyond this, since the request hasn't started.
    request->SimulateError(net::ERR_INSUFFICIENT_RESOURCES);

    // TODO(eroman): this is kinda funky -- we insert the unstarted request into
    // |pending_requests_| simply to please OnResponseCompleted().
    GlobalRequestID global_id(info->child_id(), info->request_id());
    pending_requests_[global_id] = request;
    OnResponseCompleted(request);
    return;
  }

  std::pair<int, int> pair_id(info->child_id(), info->route_id());
  BlockedRequestMap::const_iterator iter = blocked_requests_map_.find(pair_id);
  if (iter != blocked_requests_map_.end()) {
    // The request should be blocked.
    iter->second->push_back(request);
    return;
  }

  GlobalRequestID global_id(info->child_id(), info->request_id());
  pending_requests_[global_id] = request;

  // Give the resource handlers an opportunity to delay the URLRequest from
  // being started.
  //
  // There are three cases:
  //
  //   (1) if OnWillStart() returns false, the request is cancelled (regardless
  //       of whether |defer_start| was set).
  //   (2) If |defer_start| was set to true, then the request is not added
  //       into the resource queue, and will only be started in response to
  //       calling StartDeferredRequest().
  //   (3) If |defer_start| is not set, then the request is inserted into
  //       the resource_queue_ (which may pause it further, or start it).
  bool defer_start = false;
  if (!info->resource_handler()->OnWillStart(
          info->request_id(), request->url(),
          &defer_start)) {
    CancelRequestInternal(request, false);
    return;
  }

  if (!defer_start)
    InsertIntoResourceQueue(request, *info);
}

void ResourceDispatcherHost::InsertIntoResourceQueue(
    URLRequest* request,
    const ResourceDispatcherHostRequestInfo& request_info) {
  resource_queue_.AddRequest(request, request_info);

  // Make sure we have the load state monitor running
  if (!update_load_states_timer_.IsRunning()) {
    update_load_states_timer_.Start(
        TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
        this, &ResourceDispatcherHost::UpdateLoadStates);
  }
}

bool ResourceDispatcherHost::PauseRequestIfNeeded(
    ResourceDispatcherHostRequestInfo* info) {
  if (info->pause_count() > 0)
    info->set_is_paused(true);
  return info->is_paused();
}

void ResourceDispatcherHost::ResumeRequest(const GlobalRequestID& request_id) {
  PendingRequestList::iterator i = pending_requests_.find(request_id);
  if (i == pending_requests_.end())  // The request may have been destroyed
    return;

  URLRequest* request = i->second;
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  if (!info->is_paused())
    return;

  VLOG(1) << "Resuming: " << i->second->url().spec();

  info->set_is_paused(false);

  if (info->called_on_response_started()) {
    if (info->has_started_reading()) {
      OnReadCompleted(i->second, info->paused_read_bytes());
    } else {
      StartReading(request);
    }
  } else {
    OnResponseStarted(i->second);
  }
}

void ResourceDispatcherHost::StartReading(URLRequest* request) {
  // Start reading.
  int bytes_read = 0;
  if (Read(request, &bytes_read)) {
    OnReadCompleted(request, bytes_read);
  } else if (!request->status().is_io_pending()) {
    DCHECK(!InfoForRequest(request)->is_paused());
    // If the error is not an IO pending, then we're done reading.
    OnResponseCompleted(request);
  }
}

bool ResourceDispatcherHost::Read(URLRequest* request, int* bytes_read) {
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  DCHECK(!info->is_paused());

  net::IOBuffer* buf;
  int buf_size;
  if (!info->resource_handler()->OnWillRead(info->request_id(),
                                            &buf, &buf_size, -1)) {
    return false;
  }

  DCHECK(buf);
  DCHECK(buf_size > 0);

  info->set_has_started_reading(true);
  return request->Read(buf, buf_size, bytes_read);
}

void ResourceDispatcherHost::OnReadCompleted(URLRequest* request,
                                             int bytes_read) {
  DCHECK(request);
  VLOG(1) << "OnReadCompleted: " << request->url().spec();
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

  // OnReadCompleted can be called without Read (e.g., for chrome:// URLs).
  // Make sure we know that a read has begun.
  info->set_has_started_reading(true);

  if (PauseRequestIfNeeded(info)) {
    info->set_paused_read_bytes(bytes_read);
    VLOG(1) << "OnReadCompleted pausing: " << request->url().spec();
    return;
  }

  if (request->status().is_success() && CompleteRead(request, &bytes_read)) {
    // The request can be paused if we realize that the renderer is not
    // servicing messages fast enough.
    if (info->pause_count() == 0 &&
        Read(request, &bytes_read) &&
        request->status().is_success()) {
      if (bytes_read == 0) {
        CompleteRead(request, &bytes_read);
      } else {
        // Force the next CompleteRead / Read pair to run as a separate task.
        // This avoids a fast, large network request from monopolizing the IO
        // thread and starving other IO operations from running.
        info->set_paused_read_bytes(bytes_read);
        info->set_is_paused(true);
        GlobalRequestID id(info->child_id(), info->request_id());
        MessageLoop::current()->PostTask(
            FROM_HERE,
            method_runner_.NewRunnableMethod(
                &ResourceDispatcherHost::ResumeRequest, id));
        return;
      }
    }
  }

  if (PauseRequestIfNeeded(info)) {
    info->set_paused_read_bytes(bytes_read);
    VLOG(1) << "OnReadCompleted (CompleteRead) pausing: "
            << request->url().spec();
    return;
  }

  // If the status is not IO pending then we've either finished (success) or we
  // had an error.  Either way, we're done!
  if (!request->status().is_io_pending())
    OnResponseCompleted(request);
}

bool ResourceDispatcherHost::CompleteRead(URLRequest* request,
                                          int* bytes_read) {
  if (!request || !request->status().is_success()) {
    NOTREACHED();
    return false;
  }

  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  if (!info->resource_handler()->OnReadCompleted(info->request_id(),
                                                 bytes_read)) {
    CancelRequestInternal(request, false);
    return false;
  }

  return *bytes_read != 0;
}

void ResourceDispatcherHost::OnResponseCompleted(URLRequest* request) {
  VLOG(1) << "OnResponseCompleted: " << request->url().spec();
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

  // If the load for a main frame has failed, track it in a histogram,
  // since it will probably cause the user to see an error page.
  if (!request->status().is_success() &&
      info->resource_type() == ResourceType::MAIN_FRAME) {
    UMA_HISTOGRAM_CUSTOM_ENUMERATION("Net.ErrorCodesForMainFrame",
                                     -request->status().os_error(),
                                     GetAllNetErrorCodes());
  }

  std::string security_info;
  const net::SSLInfo& ssl_info = request->ssl_info();
  if (ssl_info.cert != NULL) {
    int cert_id = CertStore::GetSharedInstance()->StoreCert(ssl_info.cert,
                                                            info->child_id());
    security_info = SSLManager::SerializeSecurityInfo(
        cert_id, ssl_info.cert_status, ssl_info.security_bits,
        ssl_info.connection_status);
  }

  if (info->resource_handler()->OnResponseCompleted(info->request_id(),
                                                    request->status(),
                                                    security_info)) {
    NotifyResponseCompleted(request, info->child_id());

    // The request is complete so we can remove it.
    RemovePendingRequest(info->child_id(), info->request_id());
  }
  // If the handler's OnResponseCompleted returns false, we are deferring the
  // call until later.  We will notify the world and clean up when we resume.
}

// static
ResourceDispatcherHostRequestInfo* ResourceDispatcherHost::InfoForRequest(
    URLRequest* request) {
  // Avoid writing this function twice by casting the cosnt version.
  const URLRequest* const_request = request;
  return const_cast<ResourceDispatcherHostRequestInfo*>(
      InfoForRequest(const_request));
}

// static
const ResourceDispatcherHostRequestInfo* ResourceDispatcherHost::InfoForRequest(
    const URLRequest* request) {
  const ResourceDispatcherHostRequestInfo* info =
      static_cast<const ResourceDispatcherHostRequestInfo*>(
          request->GetUserData(NULL));
  DLOG_IF(WARNING, !info) << "Request doesn't seem to have our data";
  return info;
}

// static
bool ResourceDispatcherHost::RenderViewForRequest(const URLRequest* request,
                                                  int* render_process_host_id,
                                                  int* render_view_host_id) {
  const ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  if (!info) {
    *render_process_host_id = -1;
    *render_view_host_id = -1;
    return false;
  }

  // If the request is from the worker process, find a tab that owns the worker.
  if (info->process_type() == ChildProcessInfo::WORKER_PROCESS) {
    const WorkerProcessHost::WorkerInstance* worker_instance =
        WorkerService::GetInstance()->FindWorkerInstance(info->child_id());
    if (!worker_instance) {
      *render_process_host_id = -1;
      *render_view_host_id = -1;
      return false;
    }
    DCHECK(!worker_instance->worker_document_set()->IsEmpty());
    const WorkerDocumentSet::DocumentInfoSet& parents =
        worker_instance->worker_document_set()->documents();
    // Need to display some related UI for this network request - pick an
    // arbitrary parent to do so.
    *render_process_host_id = parents.begin()->renderer_id();
    *render_view_host_id = parents.begin()->render_view_route_id();
  } else {
    *render_process_host_id = info->child_id();
    *render_view_host_id = info->route_id();
  }
  return true;
}

void ResourceDispatcherHost::AddObserver(Observer* obs) {
  observer_list_.AddObserver(obs);
}

void ResourceDispatcherHost::RemoveObserver(Observer* obs) {
  observer_list_.RemoveObserver(obs);
}

URLRequest* ResourceDispatcherHost::GetURLRequest(
    const GlobalRequestID& request_id) const {
  // This should be running in the IO loop.
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

  PendingRequestList::const_iterator i = pending_requests_.find(request_id);
  if (i == pending_requests_.end())
    return NULL;

  return i->second;
}

static int GetCertID(URLRequest* request, int child_id) {
  if (request->ssl_info().cert) {
    return CertStore::GetSharedInstance()->StoreCert(request->ssl_info().cert,
                                                     child_id);
  }
  // If there is no SSL info attached to this request, we must either be a non
  // secure request, or the request has been canceled or failed (before the SSL
  // info was populated), or the response is an error (we have seen 403, 404,
  // and 501) made up by the proxy.
  DCHECK(!request->url().SchemeIsSecure() ||
         (request->status().status() == URLRequestStatus::CANCELED) ||
         (request->status().status() == URLRequestStatus::FAILED) ||
         ((request->response_headers()->response_code() >= 400) &&
         (request->response_headers()->response_code() <= 599)));
  return 0;
}

void ResourceDispatcherHost::NotifyResponseStarted(URLRequest* request,
                                                   int child_id) {
  // Notify the observers on the IO thread.
  FOR_EACH_OBSERVER(Observer, observer_list_, OnRequestStarted(this, request));

  int render_process_id, render_view_id;
  if (!RenderViewForRequest(request, &render_process_id, &render_view_id))
    return;

  // Notify the observers on the UI thread.
  CallRenderViewHostResourceDelegate(
      render_process_id, render_view_id,
      &RenderViewHostDelegate::Resource::DidStartReceivingResourceResponse,
      ResourceRequestDetails(request, GetCertID(request, child_id)));
}

void ResourceDispatcherHost::NotifyResponseCompleted(URLRequest* request,
                                                     int child_id) {
  // Notify the observers on the IO thread.
  FOR_EACH_OBSERVER(Observer, observer_list_,
                    OnResponseCompleted(this, request));
}

void ResourceDispatcherHost::NotifyReceivedRedirect(URLRequest* request,
                                                    int child_id,
                                                    const GURL& new_url) {
  // Notify the observers on the IO thread.
  FOR_EACH_OBSERVER(Observer, observer_list_,
                    OnReceivedRedirect(this, request, new_url));

  int render_process_id, render_view_id;
  if (!RenderViewForRequest(request, &render_process_id, &render_view_id))
    return;

  // Notify the observers on the UI thread.
  CallRenderViewHostResourceDelegate(
      render_process_id, render_view_id,
      &RenderViewHostDelegate::Resource::DidRedirectResource,
      ResourceRedirectDetails(request, GetCertID(request, child_id), new_url));
}

namespace {

// This function attempts to return the "more interesting" load state of |a|
// and |b|.  We don't have temporal information about these load states
// (meaning we don't know when we transitioned into these states), so we just
// rank them according to how "interesting" the states are.
//
// We take advantage of the fact that the load states are an enumeration listed
// in the order in which they occur during the lifetime of a request, so we can
// regard states with larger numeric values as being further along toward
// completion.  We regard those states as more interesting to report since they
// represent progress.
//
// For example, by this measure "tranferring data" is a more interesting state
// than "resolving host" because when we are transferring data we are actually
// doing something that corresponds to changes that the user might observe,
// whereas waiting for a host name to resolve implies being stuck.
//
net::LoadState MoreInterestingLoadState(net::LoadState a, net::LoadState b) {
  return (a < b) ? b : a;
}

// Carries information about a load state change.
struct LoadInfo {
  GURL url;
  net::LoadState load_state;
  uint64 upload_position;
  uint64 upload_size;
};

// Map from ProcessID+ViewID pair to LoadState
typedef std::map<std::pair<int, int>, LoadInfo> LoadInfoMap;

// Used to marshall calls to LoadStateChanged from the IO to UI threads.  We do
// them all as a single task to avoid spamming the UI thread.
class LoadInfoUpdateTask : public Task {
 public:
  virtual void Run() {
    LoadInfoMap::const_iterator i;
    for (i = info_map.begin(); i != info_map.end(); ++i) {
      RenderViewHost* view =
          RenderViewHost::FromID(i->first.first, i->first.second);
      if (view)  // The view could be gone at this point.
        view->LoadStateChanged(i->second.url, i->second.load_state,
                               i->second.upload_position,
                               i->second.upload_size);
    }
  }
  LoadInfoMap info_map;
};

}  // namespace

void ResourceDispatcherHost::UpdateLoadStates() {
  // Populate this map with load state changes, and then send them on to the UI
  // thread where they can be passed along to the respective RVHs.
  LoadInfoMap info_map;

  PendingRequestList::const_iterator i;

  // Determine the largest upload size of all requests
  // in each View (good chance it's zero).
  std::map<std::pair<int, int>, uint64> largest_upload_size;
  for (i = pending_requests_.begin(); i != pending_requests_.end(); ++i) {
    URLRequest* request = i->second;
    ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
    uint64 upload_size = info->upload_size();
    if (request->GetLoadState() != net::LOAD_STATE_SENDING_REQUEST)
      upload_size = 0;
    std::pair<int, int> key(info->child_id(), info->route_id());
    if (upload_size && largest_upload_size[key] < upload_size)
      largest_upload_size[key] = upload_size;
  }

  for (i = pending_requests_.begin(); i != pending_requests_.end(); ++i) {
    URLRequest* request = i->second;
    net::LoadState load_state = request->GetLoadState();
    ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);

    // We also poll for upload progress on this timer and send upload
    // progress ipc messages to the plugin process.
    bool update_upload_progress = MaybeUpdateUploadProgress(info, request);

    if (info->last_load_state() != load_state || update_upload_progress) {
      std::pair<int, int> key(info->child_id(), info->route_id());

      // If a request is uploading data, ignore all other requests so that the
      // upload progress takes priority for being shown in the status bar.
      if (largest_upload_size.find(key) != largest_upload_size.end() &&
          info->upload_size() < largest_upload_size[key])
        continue;

      info->set_last_load_state(load_state);

      net::LoadState to_insert;
      LoadInfoMap::iterator existing = info_map.find(key);
      if (existing == info_map.end()) {
        to_insert = load_state;
      } else {
        to_insert =
            MoreInterestingLoadState(existing->second.load_state, load_state);
        if (to_insert == existing->second.load_state)
          continue;
      }
      LoadInfo& load_info = info_map[key];
      load_info.url = request->url();
      load_info.load_state = to_insert;
      load_info.upload_size = info->upload_size();
      load_info.upload_position = request->GetUploadProgress();
    }
  }

  if (info_map.empty())
    return;

  LoadInfoUpdateTask* task = new LoadInfoUpdateTask;
  task->info_map.swap(info_map);
  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, task);
}

// Calls the ResourceHandler to send upload progress messages to the renderer.
// Returns true iff an upload progress message should be sent to the UI thread.
bool ResourceDispatcherHost::MaybeUpdateUploadProgress(
    ResourceDispatcherHostRequestInfo *info,
    URLRequest *request) {

  if (!info->upload_size() || info->waiting_for_upload_progress_ack())
    return false;

  uint64 size = info->upload_size();
  uint64 position = request->GetUploadProgress();
  if (position == info->last_upload_position())
    return false;  // no progress made since last time

  const uint64 kHalfPercentIncrements = 200;
  const TimeDelta kOneSecond = TimeDelta::FromMilliseconds(1000);

  uint64 amt_since_last = position - info->last_upload_position();
  TimeDelta time_since_last = TimeTicks::Now() - info->last_upload_ticks();

  bool is_finished = (size == position);
  bool enough_new_progress = (amt_since_last > (size / kHalfPercentIncrements));
  bool too_much_time_passed = time_since_last > kOneSecond;

  if (is_finished || enough_new_progress || too_much_time_passed) {
    if (request->load_flags() & net::LOAD_ENABLE_UPLOAD_PROGRESS) {
      info->resource_handler()->OnUploadProgress(info->request_id(),
                                                 position, size);
      info->set_waiting_for_upload_progress_ack(true);
    }
    info->set_last_upload_ticks(TimeTicks::Now());
    info->set_last_upload_position(position);
    return true;
  }
  return false;
}

void ResourceDispatcherHost::BlockRequestsForRoute(int child_id, int route_id) {
  std::pair<int, int> key(child_id, route_id);
  DCHECK(blocked_requests_map_.find(key) == blocked_requests_map_.end()) <<
      "BlockRequestsForRoute called  multiple time for the same RVH";
  blocked_requests_map_[key] = new BlockedRequestsList();
}

void ResourceDispatcherHost::ResumeBlockedRequestsForRoute(int child_id,
                                                           int route_id) {
  ProcessBlockedRequestsForRoute(child_id, route_id, false);
}

void ResourceDispatcherHost::CancelBlockedRequestsForRoute(int child_id,
                                                           int route_id) {
  ProcessBlockedRequestsForRoute(child_id, route_id, true);
}

void ResourceDispatcherHost::ProcessBlockedRequestsForRoute(
    int child_id,
    int route_id,
    bool cancel_requests) {
  BlockedRequestMap::iterator iter = blocked_requests_map_.find(
      std::pair<int, int>(child_id, route_id));
  if (iter == blocked_requests_map_.end()) {
    // It's possible to reach here if the renderer crashed while an interstitial
    // page was showing.
    return;
  }

  BlockedRequestsList* requests = iter->second;

  // Removing the vector from the map unblocks any subsequent requests.
  blocked_requests_map_.erase(iter);

  for (BlockedRequestsList::iterator req_iter = requests->begin();
       req_iter != requests->end(); ++req_iter) {
    // Remove the memory credit that we added when pushing the request onto
    // the blocked list.
    URLRequest* request = *req_iter;
    ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
    IncrementOutstandingRequestsMemoryCost(-1 * info->memory_cost(),
                                           info->child_id());
    if (cancel_requests)
      delete request;
    else
      BeginRequestInternal(request);
  }

  delete requests;
}

bool ResourceDispatcherHost::IsValidRequest(URLRequest* request) {
  if (!request)
    return false;
  ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
  return pending_requests_.find(
      GlobalRequestID(info->child_id(), info->request_id())) !=
      pending_requests_.end();
}

// static
bool ResourceDispatcherHost::IsResourceDispatcherHostMessage(
    const IPC::Message& message) {
  switch (message.type()) {
    case ViewHostMsg_RequestResource::ID:
    case ViewHostMsg_CancelRequest::ID:
    case ViewHostMsg_FollowRedirect::ID:
    case ViewHostMsg_ClosePage_ACK::ID:
    case ViewHostMsg_ReleaseDownloadedFile::ID:
    case ViewHostMsg_DataReceived_ACK::ID:
    case ViewHostMsg_DataDownloaded_ACK::ID:
    case ViewHostMsg_UploadProgress_ACK::ID:
    case ViewHostMsg_SyncLoad::ID:
      return true;

    default:
      break;
  }

  return false;
}

// static
void ResourceDispatcherHost::ApplyExtensionLocalizationFilter(
    const GURL& url,
    const ResourceType::Type& resource_type,
    ResourceDispatcherHostRequestInfo* request_info) {
  // Apply filter to chrome extension CSS files.
  if (url.SchemeIs(chrome::kExtensionScheme) &&
      resource_type == ResourceType::STYLESHEET)
    request_info->set_replace_extension_localization_templates();
}

// static
net::RequestPriority ResourceDispatcherHost::DetermineRequestPriority(
    ResourceType::Type type) {
  // Determine request priority based on how critical this resource typically
  // is to user-perceived page load performance. Important considerations are:
  // * Can this resource block the download of other resources.
  // * Can this resource block the rendering of the page.
  // * How useful is the page to the user if this resource is not loaded yet.
  switch (type) {
    // Main frames are the highest priority because they can block nearly every
    // type of other resource and there is no useful display without them.
    // Sub frames are a close second, however it is a common pattern to wrap
    // ads in an iframe or even in multiple nested iframes. It is worth
    // investigating if there is a better priority for them.
    case ResourceType::MAIN_FRAME:
    case ResourceType::SUB_FRAME:
      return net::HIGHEST;

    // Stylesheets and scripts can block rendering and loading of other
    // resources. Fonts can block text from rendering.
    case ResourceType::STYLESHEET:
    case ResourceType::SCRIPT:
    case ResourceType::FONT_RESOURCE:
      return net::MEDIUM;

    // Sub resources, objects and media are lower priority than potentially
    // blocking stylesheets, scripts and fonts, but are higher priority than
    // images because if they exist they are probably more central to the page
    // focus than images on the page.
    case ResourceType::SUB_RESOURCE:
    case ResourceType::OBJECT:
    case ResourceType::MEDIA:
    case ResourceType::WORKER:
    case ResourceType::SHARED_WORKER:
      return net::LOW;

    // Images are the "lowest" priority because they typically do not block
    // downloads or rendering and most pages have some useful content without
    // them.
    case ResourceType::IMAGE:
      return net::LOWEST;

    // Prefetches are at a lower priority than even LOWEST, since they
    // are not even required for rendering of the current page.
    case ResourceType::PREFETCH:
      return net::IDLE;

    default:
      // When new resource types are added, their priority must be considered.
      NOTREACHED();
      return net::LOW;
  }
}

// static
bool ResourceDispatcherHost::is_prefetch_enabled() {
  return is_prefetch_enabled_;
}

// static
void ResourceDispatcherHost::set_is_prefetch_enabled(bool value) {
  is_prefetch_enabled_ = value;
}

// static
bool ResourceDispatcherHost::is_prefetch_enabled_ = false;