content/browser/loader/resource_dispatcher_host_impl.h

// Copyright (c) 2012 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.

// This is the browser side of the resource dispatcher, it receives requests
// from the child process (i.e. [Renderer, Plugin, Worker]ProcessHost), and
// dispatches them to URLRequests. It then forwards the messages from the
// URLRequests back to the correct process for handling.
//
// See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading

#ifndef CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_
#define CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_

#include <stdint.h>

#include <map>
#include <memory>
#include <string>
#include <vector>

#include "base/callback_forward.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/optional.h"
#include "base/single_thread_task_runner.h"
#include "base/time/time.h"
#include "content/browser/blob_storage/chrome_blob_storage_context.h"
#include "content/browser/loader/resource_loader_delegate.h"
#include "content/common/content_export.h"
#include "content/public/browser/global_request_id.h"
#include "content/public/browser/global_routing_id.h"
#include "content/public/browser/resource_dispatcher_host.h"
#include "content/public/browser/resource_request_info.h"
#include "content/public/browser/stream_handle.h"
#include "content/public/common/previews_state.h"
#include "content/public/common/resource_type.h"
#include "net/base/load_states.h"
#include "net/base/request_priority.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "services/network/keepalive_statistics_recorder.h"
#include "services/network/public/mojom/url_loader.mojom.h"
#include "third_party/blink/public/mojom/fetch/fetch_api_request.mojom.h"
#include "url/gurl.h"

namespace base {
class OneShotTimer;
}

namespace net {
class HttpRequestHeaders;
class URLRequest;
class URLRequestContextGetter;
}

namespace network {
class ResourceScheduler;
class ScopedThrottlingToken;
}  // namespace network

namespace storage {
class FileSystemContext;
}

namespace content {
class AppCacheNavigationHandleCore;
class AppCacheService;
class LoaderDelegate;
class NavigationUIData;
class ResourceContext;
class ResourceDispatcherHostDelegate;
class ResourceLoader;
class ResourceHandler;
class ResourceMessageDelegate;
class ResourceRequesterInfo;
class ResourceRequestInfoImpl;
struct NavigationRequestInfo;
struct Referrer;
struct ResourceRequest;

using CreateDownloadHandlerIntercept =
    base::Callback<std::unique_ptr<ResourceHandler>(net::URLRequest*)>;

class CONTENT_EXPORT ResourceDispatcherHostImpl
    : public ResourceDispatcherHost,
      public ResourceLoaderDelegate {
 public:
  // This constructor should be used if we want downloads to work correctly.
  // TODO(ananta)
  // Work on moving creation of download handlers out of
  // ResourceDispatcherHostImpl.
  ResourceDispatcherHostImpl(
      CreateDownloadHandlerIntercept download_handler_intercept,
      const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_runner,
      bool enable_resource_scheduler);
  ResourceDispatcherHostImpl();
  ~ResourceDispatcherHostImpl() override;

  // Returns the current ResourceDispatcherHostImpl. May return NULL if it
  // hasn't been created yet.
  static ResourceDispatcherHostImpl* Get();

  // ResourceDispatcherHost implementation:
  void SetDelegate(ResourceDispatcherHostDelegate* delegate) override;
  void SetAllowCrossOriginAuthPrompt(bool value) override;
  void RegisterInterceptor(const std::string& http_header,
                           const std::string& starts_with,
                           const InterceptorCallback& interceptor) override;
  void ReprioritizeRequest(net::URLRequest* request,
                           net::RequestPriority priority) override;

  // Puts the resource dispatcher host in an inactive state (unable to begin
  // new requests).  Cancels all pending requests.
  void Shutdown();

  // Force cancels any pending requests for the given |context|. This is
  // necessary to ensure that before |context| goes away, all requests
  // for it are dead.
  void CancelRequestsForContext(ResourceContext* context);

  // Cancels the given request if it still exists.
  void CancelRequest(int child_id, int request_id);

  // Returns the number of pending requests. This is designed for the unittests
  int pending_requests() const {
    return static_cast<int>(pending_loaders_.size());
  }

  // Intended for unit-tests only. Overrides the outstanding requests bound.
  void set_max_outstanding_requests_cost_per_process(int limit) {
    max_outstanding_requests_cost_per_process_ = limit;
  }
  void set_max_num_in_flight_requests_per_process(int limit) {
    max_num_in_flight_requests_per_process_ = limit;
  }
  void set_max_num_in_flight_requests(int limit) {
    max_num_in_flight_requests_ = limit;
  }

  // The average private bytes increase of the browser for each new pending
  // request. Experimentally obtained.
  static const int kAvgBytesPerOutstandingRequest = 4400;

  // Called when a RenderViewHost is created.
  static void OnRenderViewHostCreated(
      int child_id,
      int route_id,
      net::URLRequestContextGetter* url_request_context_getter);

  // Called when a RenderViewHost is deleted.
  static void OnRenderViewHostDeleted(int child_id, int route_id);

  // Force cancels any pending requests for the given process.
  void CancelRequestsForProcess(int child_id);

  void OnUserGesture();

  // Retrieves a net::URLRequest.  Must be called from the IO thread.
  net::URLRequest* GetURLRequest(const GlobalRequestID& request_id);

  void RemovePendingRequest(int child_id, int request_id);

  // Causes all new requests for the route identified by |routing_id| to be
  // blocked (not being started) until ResumeBlockedRequestsForRoute is called.
  void BlockRequestsForRoute(const GlobalFrameRoutingId& global_routing_id);

  // Resumes any blocked request for the specified route id.
  void ResumeBlockedRequestsForRoute(
      const GlobalFrameRoutingId& global_routing_id);

  // Cancels any blocked request for the specified route id.
  void CancelBlockedRequestsForRoute(
      const GlobalFrameRoutingId& global_routing_id);

  // Indicates whether third-party sub-content can pop-up HTTP basic auth
  // dialog boxes.
  bool allow_cross_origin_auth_prompt();

  ResourceDispatcherHostDelegate* delegate() {
    return delegate_;
  }

  // Must be called after the ResourceRequestInfo has been created
  // and associated with the request.
  // This is marked virtual so it can be overriden in testing.
  // TODO(ananta)
  // This method should be removed or moved outside this class.
  virtual std::unique_ptr<ResourceHandler> CreateResourceHandlerForDownload(
      net::URLRequest* request,
      bool is_content_initiated,
      bool must_download,
      bool is_new_request);

  // Called to determine whether the response to |request| should be intercepted
  // and handled as a stream. Streams are used to pass direct access to a
  // resource response to another application (e.g. a web page) without being
  // handled by the browser itself. If the request should be intercepted as a
  // stream, a StreamResourceHandler is returned which provides access to the
  // response.
  //
  // This function must be called after the ResourceRequestInfo has been created
  // and associated with the request. If |payload| is set to a non-empty value,
  // the caller must send it to the old resource handler instead of cancelling
  // it.
  virtual std::unique_ptr<ResourceHandler> MaybeInterceptAsStream(
      net::URLRequest* request,
      network::ResourceResponse* response,
      std::string* payload);

  network::ResourceScheduler* scheduler() { return scheduler_.get(); }

  // Called by a ResourceHandler when it's ready to start reading data and
  // sending it to the renderer. Returns true if there are enough file
  // descriptors available for the shared memory buffer. If false is returned,
  // the request should cancel.
  bool HasSufficientResourcesForRequest(net::URLRequest* request);

  // Called by a ResourceHandler after it has finished its request and is done
  // using its shared memory buffer. Frees up that file descriptor to be used
  // elsewhere.
  void FinishedWithResourcesForRequest(net::URLRequest* request);

  // PlzNavigate: Begins a request for NavigationURLLoader. |loader| is the
  // loader to attach to the leaf resource handler. |global_request_id| needs to
  // be created by MakeGlobalRequestID() before calling this method.
  void BeginNavigationRequest(
      ResourceContext* resource_context,
      net::URLRequestContext* request_context,
      storage::FileSystemContext* upload_file_system_context,
      const NavigationRequestInfo& info,
      std::unique_ptr<NavigationUIData> navigation_ui_data,
      network::mojom::URLLoaderClientPtr url_loader_client,
      network::mojom::URLLoaderRequest url_loader_request,
      AppCacheNavigationHandleCore* appcache_handle_core,
      uint32_t url_loader_options,
      net::RequestPriority net_priority,
      const GlobalRequestID& global_request_id);

  int num_in_flight_requests_for_testing() const {
    return num_in_flight_requests_;
  }

  // Sets the LoaderDelegate, which must outlive this object. Ownership is not
  // transferred. The LoaderDelegate should be interacted with on the IO thread.
  void SetLoaderDelegate(LoaderDelegate* loader_delegate);

  void OnRenderFrameDeleted(const GlobalFrameRoutingId& global_routing_id);

  // Called when loading a request with mojo.
  void OnRequestResourceWithMojo(
      ResourceRequesterInfo* requester_info,
      int32_t routing_id,
      int32_t request_id,
      uint32_t options,
      const network::ResourceRequest& request,
      network::mojom::URLLoaderRequest mojo_request,
      network::mojom::URLLoaderClientPtr url_loader_client,
      const net::NetworkTrafficAnnotationTag& traffic_annotation);

  // Helper function for initializing the |request| passed in. By initializing
  // we mean setting the |referrer| on the |request|, associating the
  // ResourceRequestInfoImpl structure with the |request|, etc.
  // This function should be called for invoking the BeginURLRequest() function
  // to initiate a URL request.
  void InitializeURLRequest(net::URLRequest* request,
                            const Referrer& referrer,
                            bool is_download,
                            int render_process_host_id,
                            int render_view_routing_id,
                            int render_frame_routing_id,
                            int frame_tree_node_id,
                            PreviewsState previews_state,
                            ResourceContext* context);

  // Helper function for initiating a URL request. The |is_download| and
  // |is_content_initiated and |do_not_prompt_for_login| parameters are
  // specific to download requests.
  // TODO(ananta)
  // Look into a better way of passing these parameters in.
  // Please note that the InitializeURLRequest() function needs to be called
  // called to initialize the request before calling this function.
  void BeginURLRequest(std::unique_ptr<net::URLRequest> request,
                       std::unique_ptr<ResourceHandler> handler,
                       bool is_download,
                       bool is_content_initiated,
                       bool do_not_prompt_for_login,
                       ResourceContext* context);

  bool is_shutdown() const { return is_shutdown_; }

  // Creates a new request ID for browser initiated requests. See the comments
  // of |request_id_| for the details. Must be called on the IO thread.
  int MakeRequestID();

  // Creates a new global request ID for browser initiated requests. The ID
  // is consistent with the request id created by MakeRequestID(). Must be
  // called on the IO thread.
  GlobalRequestID MakeGlobalRequestID();

  // Cancels a request as requested by a renderer. This function is called when
  // a mojo connection is lost.
  // Note that this cancel is subtly different from the other CancelRequest
  // methods in this file, which also tear down the loader.
  void CancelRequestFromRenderer(GlobalRequestID request_id);

  scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner() const {
    return io_thread_task_runner_;
  }

  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner() const {
    return main_thread_task_runner_;
  }

  network::KeepaliveStatisticsRecorder* keepalive_statistics_recorder() {
    return &keepalive_statistics_recorder_;
  }

  // Checks if needs to prompt for login.
  bool DoNotPromptForLogin(ResourceType resource_type,
                           const GURL& url,
                           const GURL& site_for_cookies);

 private:
  class ScheduledResourceRequestAdapter;
  friend class NetworkServiceClient;
  friend class ResourceDispatcherHostTest;

  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           TestBlockedRequestsProcessDies);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           CalculateApproximateMemoryCost);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           DetachableResourceTimesOut);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           TestProcessCancelDetachableTimesOut);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest, CancelRequestsForRoute);
  FRIEND_TEST_ALL_PREFIXES(SitePerProcessIgnoreCertErrorsBrowserTest,
                           CrossSiteRedirectCertificateStore);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest, LoadInfo);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest, LoadInfoSamePriority);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest, LoadInfoUploadProgress);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest, LoadInfoTwoRenderViews);

  struct OustandingRequestsStats {
    int memory_cost;
    int num_requests;
  };

  friend class ShutdownTask;
  friend class ResourceMessageDelegate;

  // Information about status of a ResourceLoader.
  struct CONTENT_EXPORT LoadInfo {
    LoadInfo();
    LoadInfo(const LoadInfo& other);
    ~LoadInfo();

    ResourceRequestInfo::WebContentsGetter web_contents_getter;

    // Comes directly from GURL::host() to avoid copying an entire GURL between
    // threads.
    std::string host;

    net::LoadStateWithParam load_state;
    uint64_t upload_position;
    uint64_t upload_size;
  };

  // Map from WebContents* to the "most interesting" LoadState.
  typedef std::map<WebContents*, LoadInfo> LoadInfoMap;
  typedef std::vector<LoadInfo> LoadInfoList;

  // Information about a HTTP header interceptor.
  struct HeaderInterceptorInfo {
    // Structure is sufficiently complicated to require the constructor
    // destructor definitions in the cc file.
    HeaderInterceptorInfo();
    ~HeaderInterceptorInfo();
    HeaderInterceptorInfo(const HeaderInterceptorInfo& other);

    // Used to prefix match the value of the http header.
    std::string starts_with;
    // The interceptor.
    InterceptorCallback interceptor;
  };

  // Map from HTTP header to its information HeaderInterceptorInfo.
  typedef std::map<std::string, HeaderInterceptorInfo> HeaderInterceptorMap;

  // ResourceLoaderDelegate implementation:
  std::unique_ptr<LoginDelegate> CreateLoginDelegate(
      ResourceLoader* loader,
      net::AuthChallengeInfo* auth_info) override;
  bool HandleExternalProtocol(ResourceLoader* loader, const GURL& url) override;
  void DidStartRequest(ResourceLoader* loader) override;
  void DidReceiveRedirect(ResourceLoader* loader,
                          const GURL& new_url,
                          network::ResourceResponse* response) override;
  void DidReceiveResponse(ResourceLoader* loader,
                          network::ResourceResponse* response) override;
  void DidFinishLoading(ResourceLoader* loader) override;

  // An init helper that runs on the IO thread.
  void OnInit();

  // A shutdown helper that runs on the IO thread.
  void OnShutdown();

  // Helper function for URL requests.
  void BeginRequestInternal(
      std::unique_ptr<net::URLRequest> request,
      std::unique_ptr<ResourceHandler> handler,
      bool is_initiated_by_fetch_api,
      std::unique_ptr<network::ScopedThrottlingToken> throttling_token);

  void StartLoading(ResourceRequestInfoImpl* info,
                    std::unique_ptr<ResourceLoader> loader);

  // We keep track of how much memory each request needs and how many requests
  // are issued by each renderer. These are known as OustandingRequestStats.
  // Memory limits apply to all requests sent to us by the renderers. There is a
  // limit for each renderer. File descriptor limits apply to requests that are
  // receiving their body. These are known as in-flight requests. There is a
  // global limit that applies for the browser process. Each render is allowed
  // to use up to a fraction of that.

  // Returns the OustandingRequestsStats for |info|'s renderer, or an empty
  // struct if that renderer has no outstanding requests.
  OustandingRequestsStats GetOutstandingRequestsStats(
      ResourceRequestInfoImpl* info);

  // Updates |outstanding_requests_stats_map_| with the specified |stats| for
  // the renderer that made the request in |info|.
  void UpdateOutstandingRequestsStats(ResourceRequestInfoImpl* info,
                                      const OustandingRequestsStats& stats);

  // Called every time an outstanding request is created or deleted. |count|
  // indicates whether the request is new or deleted. |count| must be 1 or -1.
  OustandingRequestsStats IncrementOutstandingRequestsMemory(
      int count,
      ResourceRequestInfoImpl* info);

  // Called when an in flight request allocates or releases a shared memory
  // buffer. |count| indicates whether the request is issuing or finishing.
  // |count| must be 1 or -1.
  OustandingRequestsStats IncrementOutstandingRequestsCount(
      int count,
      ResourceRequestInfoImpl* info);

  // Estimate how much heap space |request| will consume to run.
  static int CalculateApproximateMemoryCost(net::URLRequest* request);

  // Force cancels any pending requests for the given route id.  This method
  // acts like CancelRequestsForProcess when the |route_id| member of
  // |routing_id| is MSG_ROUTING_NONE.
  void CancelRequestsForRoute(const GlobalFrameRoutingId& global_routing_id);

  // The list of all requests that we have pending. This list is not really
  // optimized, and assumes that we have relatively few requests pending at once
  // since some operations require brute-force searching of the list.
  //
  // It may be enhanced in the future to provide some kind of prioritization
  // mechanism. We should also consider a hashtable or binary tree if it turns
  // out we have a lot of things here.
  using LoaderMap = std::map<GlobalRequestID, std::unique_ptr<ResourceLoader>>;

  // Deletes the pending request identified by the iterator passed in.
  // This function will invalidate the iterator passed in. Callers should
  // not rely on this iterator being valid on return.
  void RemovePendingLoader(const LoaderMap::iterator& iter);

  // This function returns true if the LoadInfo of |a| is "more interesting"
  // than the LoadInfo of |b|.  The load that is currently sending the larger
  // request body is considered more interesting.  If neither request is
  // sending a body (Neither request has a body, or any request that has a body
  // is not currently sending the body), the request that is further along is
  // considered more interesting.
  //
  // This takes advantage of the fact that the load states are an enumeration
  // listed in the order in which they usually occur during the lifetime of a
  // request, so states with larger numeric values are generally further along
  // toward completion.
  //
  // For example, by this measure "tranferring data" is a more interesting state
  // than "resolving host" because when transferring data something is being
  // done that corresponds to changes that the user might observe, whereas
  // waiting for a host name to resolve implies being stuck.
  static bool LoadInfoIsMoreInteresting(const LoadInfo& a, const LoadInfo& b);

  // Picks the most interesting LoadInfos from the given array per WebContents
  // and calls the delegate with them.
  static void UpdateLoadStateOnUI(LoaderDelegate* loader_delegate,
                                  std::unique_ptr<LoadInfoList> infos);

  // Returns the most interesting LoadInfos from the given array per
  // WebContents.
  static std::unique_ptr<LoadInfoMap> PickMoreInterestingLoadInfos(
      std::unique_ptr<LoadInfoList> infos);

  // Gets the most interesting LoadInfos for each GlobalFrameRoutingIds.
  // Includes the LoadInfo for all navigation requests, which may not have valid
  // frame ids.
  //
  // We aggregate per-frame on the IO thread, and per-WebContents on the UI
  // thread. The IO thread aggregation is used to avoid copying state for every
  // request across threads.
  std::unique_ptr<LoadInfoList> GetInterestingPerFrameLoadInfos();

  // Checks all pending requests and updates the load info if necessary.
  void UpdateLoadInfo();

  // Invoked on the IO thread once load state has been updated on the UI thread,
  // starts timer call UpdateLoadInfo() again, if needed.
  void AckUpdateLoadInfo();

  // Starts the timer to call UpdateLoadInfo(), if timer isn't already running,
  // |waiting_on_load_state_ack_| is false, and there are live ResourceLoaders.
  void MaybeStartUpdateLoadInfoTimer();

  // Resumes or cancels (if |cancel_requests| is true) any blocked requests.
  void ProcessBlockedRequestsForRoute(
      const GlobalFrameRoutingId& global_routing_id,
      bool cancel_requests);

  void OnRequestResourceInternal(
      ResourceRequesterInfo* requester_info,
      int routing_id,
      int request_id,
      bool is_sync_load,
      const network::ResourceRequest& request_data,
      uint32_t url_loader_options,
      network::mojom::URLLoaderRequest mojo_request,
      network::mojom::URLLoaderClientPtr url_loader_client,
      const net::NetworkTrafficAnnotationTag& traffic_annotation);

  bool IsRequestIDInUse(const GlobalRequestID& id) const;

  void BeginRequest(ResourceRequesterInfo* requester_info,
                    int request_id,
                    const network::ResourceRequest& request_data,
                    bool is_sync_load,
                    int route_id,
                    uint32_t url_loader_options,
                    network::mojom::URLLoaderRequest mojo_request,
                    network::mojom::URLLoaderClientPtr url_loader_client,
                    const net::NetworkTrafficAnnotationTag& traffic_annotation);

  // There are requests which need decisions to be made like the following:
  // Whether the presence of certain HTTP headers like the Origin header are
  // valid, etc. These requests may need to be aborted based on these
  // decisions which could be time consuming. We allow for these decisions
  // to be made asynchronously. The request proceeds when we hear back from
  // the interceptors about whether to continue or not.
  // The |interceptor_result| indicates whether the request should be continued
  // or aborted, and in the latter case whether the renderer should be killed.
  void ContinuePendingBeginRequest(
      scoped_refptr<ResourceRequesterInfo> requester_info,
      int request_id,
      const network::ResourceRequest& request_data,
      bool is_sync_load,
      int route_id,
      const net::HttpRequestHeaders& headers,
      uint32_t url_loader_options,
      network::mojom::URLLoaderRequest mojo_request,
      network::mojom::URLLoaderClientPtr url_loader_client,
      BlobHandles blob_handles,
      const net::NetworkTrafficAnnotationTag& traffic_annotation,
      HeaderInterceptorResult interceptor_result);

  // Creates a ResourceHandler to be used by BeginRequest() for normal resource
  // loading.
  std::unique_ptr<ResourceHandler> CreateResourceHandler(
      ResourceRequesterInfo* requester_info,
      net::URLRequest* request,
      const network::ResourceRequest& request_data,
      int route_id,
      int child_id,
      ResourceContext* resource_context,
      uint32_t url_loader_options,
      network::mojom::URLLoaderRequest mojo_request,
      network::mojom::URLLoaderClientPtr url_loader_client);

  // Wraps |handler| in the standard resource handlers for normal resource
  // loading and navigation requests. This adds MimeTypeResourceHandler and
  // ResourceThrottles.
  std::unique_ptr<ResourceHandler> AddStandardHandlers(
      net::URLRequest* request,
      ResourceType resource_type,
      ResourceContext* resource_context,
      network::mojom::FetchRequestMode fetch_request_mode,
      blink::mojom::RequestContextType fetch_request_context_type,
      uint32_t url_loader_options,
      AppCacheService* appcache_service,
      int child_id,
      int route_id,
      std::unique_ptr<ResourceHandler> handler);

  // Creates ResourceRequestInfoImpl for a download or page save.
  // |download| should be true if the request is a file download.
  ResourceRequestInfoImpl* CreateRequestInfo(int child_id,
                                             int render_view_route_id,
                                             int render_frame_route_id,
                                             int frame_tree_node_id,
                                             PreviewsState previews_state,
                                             bool download,
                                             ResourceContext* context);

  // Relationship of resource being authenticated with the top level page.
  enum HttpAuthRelationType {
    HTTP_AUTH_RELATION_TOP,            // Top-level page itself
    HTTP_AUTH_RELATION_SAME_DOMAIN,    // Sub-content from same domain
    HTTP_AUTH_RELATION_BLOCKED_CROSS,  // Blocked Sub-content from cross domain
    HTTP_AUTH_RELATION_ALLOWED_CROSS,  // Allowed Sub-content per command line
    HTTP_AUTH_RELATION_LAST
  };

  HttpAuthRelationType HttpAuthRelationTypeOf(const GURL& request_url,
                                              const GURL& first_party);

  ResourceLoader* GetLoader(const GlobalRequestID& id) const;
  ResourceLoader* GetLoader(int child_id, int request_id) const;

  // Consults the RendererSecurity policy to determine whether the
  // ResourceDispatcherHostImpl 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(int child_id,
                            const network::ResourceRequest& request_data,
                            const net::HttpRequestHeaders& headers,
                            ResourceRequesterInfo* requester_info,
                            ResourceContext* resource_context);

  // Notifies the ResourceDispatcherHostDelegate about a download having
  // started. The function returns the |handler| passed in, if the download
  // is not throttled. If the download is to be throttled (Decided by the
  // delegate) the function returns a ThrottlingResourceHandler to handle the
  // download.
  std::unique_ptr<ResourceHandler> HandleDownloadStarted(
      net::URLRequest* request,
      std::unique_ptr<ResourceHandler> handler,
      bool is_content_initiated,
      bool must_download,
      bool is_new_request);

  void RunAuthRequiredCallback(
      GlobalRequestID request_id,
      const base::Optional<net::AuthCredentials>& credentials);

  static void RecordFetchRequestMode(const GURL& url,
                                     base::StringPiece method,
                                     network::mojom::FetchRequestMode mode);

  static net::NetworkTrafficAnnotationTag GetTrafficAnnotation();

  LoaderMap pending_loaders_;

  // A timer that periodically calls UpdateLoadInfo while |pending_loaders_| is
  // not empty, at least one RenderViewHost is loading, and not waiting on an
  // ACK from the UI thread for the last sent LoadInfoList.
  std::unique_ptr<base::OneShotTimer> update_load_info_timer_;
  // True if a LoadInfoList has been sent to the UI thread, but has yet to be
  // acknowledged.
  bool waiting_on_load_state_ack_ = false;

  // Request ID for browser initiated requests. request_ids generated by
  // child processes are counted up from 0, while browser created requests
  // start at -2 and go down from there. (We need to start at -2 because -1 is
  // used as a special value all over the resource_dispatcher_host for
  // uninitialized variables.) This way, we no longer have the unlikely (but
  // observed in the real world!) event where we have two requests with the same
  // request_id_.
  int request_id_;

  // True if the resource dispatcher host has been shut down.
  bool is_shutdown_;

  const bool enable_resource_scheduler_;

  using BlockedLoadersList = std::vector<std::unique_ptr<ResourceLoader>>;
  using BlockedLoadersMap =
      std::map<GlobalFrameRoutingId, std::unique_ptr<BlockedLoadersList>>;
  BlockedLoadersMap blocked_loaders_map_;

  // Maps the child_ids to the approximate number of bytes
  // being used to service its resource requests. No entry implies 0 cost.
  typedef std::map<int, OustandingRequestsStats> OutstandingRequestsStatsMap;
  OutstandingRequestsStatsMap outstanding_requests_stats_map_;

  // |num_in_flight_requests_| is the total number of requests currently issued
  // summed across all renderers.
  int num_in_flight_requests_;

  // |max_num_in_flight_requests_| is the upper bound on how many requests
  // can be in flight at once. It's based on the maximum number of file
  // descriptors open per process. We need a global limit for the browser
  // process.
  int max_num_in_flight_requests_;

  // |max_num_in_flight_requests_| is the upper bound on how many requests
  // can be issued at once. It's based on the maximum number of file
  // descriptors open per process. We need a per-renderer limit so that no
  // single renderer can hog the browser's limit.
  int max_num_in_flight_requests_per_process_;

  // |max_outstanding_requests_cost_per_process_| is the upper bound on how
  // many outstanding requests can be issued per child process host.
  // The constraint is expressed in terms of bytes (where the cost of
  // individual requests is given by CalculateApproximateMemoryCost).
  // The total number of outstanding requests is roughly:
  //   (max_outstanding_requests_cost_per_process_ /
  //       kAvgBytesPerOutstandingRequest)
  int max_outstanding_requests_cost_per_process_;

  // Time of the last user gesture. Stored so that we can add a load
  // flag to requests occurring soon after a gesture to indicate they
  // may be because of explicit user action.
  base::TimeTicks last_user_gesture_time_;

  ResourceDispatcherHostDelegate* delegate_;

  LoaderDelegate* loader_delegate_;

  bool allow_cross_origin_auth_prompt_;

  std::unique_ptr<network::ResourceScheduler> scheduler_;

  // Used to invoke an interceptor for the HTTP header.
  HeaderInterceptorMap http_header_interceptor_map_;

  network::KeepaliveStatisticsRecorder keepalive_statistics_recorder_;

  // Points to the registered download handler intercept.
  CreateDownloadHandlerIntercept create_download_handler_intercept_;

  // Task runner for the main thread.
  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;

  // Task runner for the IO thead.
  scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner_;

  // Used on the IO thread to allow PostTaskAndReply replies to the IO thread
  // to be abandoned if they run after OnShutdown().
  base::WeakPtrFactory<ResourceDispatcherHostImpl> weak_factory_on_io_;

  DISALLOW_COPY_AND_ASSIGN(ResourceDispatcherHostImpl);
};

}  // namespace content

#endif  // CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_