Revert of Revert CL 117933003. Re-add resource speculative prefetching code.

chrome/browser/predictors/resource_prefetcher.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_
-#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_
-
-#include <list>
-#include <map>
-#include <vector>
-
-#include "base/gtest_prod_util.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/scoped_vector.h"
-#include "base/threading/thread_checker.h"
-#include "chrome/browser/predictors/resource_prefetch_common.h"
-#include "net/url_request/redirect_info.h"
-#include "net/url_request/url_request.h"
-#include "url/gurl.h"
-
-namespace net {
-class URLRequestContext;
-}
-
-namespace predictors {
-
-// Responsible for prefetching resources for a single navigation based on the
-// input list of resources.
-//  - Limits the max number of resources in flight for any host and also across
-//    hosts.
-//  - When stopped, will wait for the pending requests to finish.
-//  - Lives entirely on the IO thread.
-class ResourcePrefetcher : public net::URLRequest::Delegate {
- public:
-  // Denotes the prefetch request for a single subresource.
-  struct Request {
-    explicit Request(const GURL& i_resource_url);
-    Request(const Request& other);
-
-    enum PrefetchStatus {
-      PREFETCH_STATUS_NOT_STARTED,
-      PREFETCH_STATUS_STARTED,
-
-      // Cancellation reasons.
-      PREFETCH_STATUS_REDIRECTED,
-      PREFETCH_STATUS_AUTH_REQUIRED,
-      PREFETCH_STATUS_CERT_REQUIRED,
-      PREFETCH_STATUS_CERT_ERROR,
-      PREFETCH_STATUS_CANCELLED,
-      PREFETCH_STATUS_FAILED,
-
-      // Successful prefetch states.
-      PREFETCH_STATUS_FROM_CACHE,
-      PREFETCH_STATUS_FROM_NETWORK
-    };
-
-    enum UsageStatus {
-      USAGE_STATUS_NOT_REQUESTED,
-      USAGE_STATUS_FROM_CACHE,
-      USAGE_STATUS_FROM_NETWORK,
-      USAGE_STATUS_NAVIGATION_ABANDONED
-    };
-
-    GURL resource_url;
-    PrefetchStatus prefetch_status;
-    UsageStatus usage_status;
-  };
-  typedef ScopedVector<Request> RequestVector;
-
-  // Used to communicate when the prefetching is done. All methods are invoked
-  // on the IO thread.
-  class Delegate {
-   public:
-    virtual ~Delegate() { }
-
-    // Called when the ResourcePrefetcher is finished, i.e. there is nothing
-    // pending in flight. Should take ownership of |requests|.
-    virtual void ResourcePrefetcherFinished(
-        ResourcePrefetcher* prefetcher,
-        RequestVector* requests) = 0;
-
-    virtual net::URLRequestContext* GetURLRequestContext() = 0;
-  };
-
-  // |delegate| has to outlive the ResourcePrefetcher. The ResourcePrefetcher
-  // takes ownership of |requests|.
-  ResourcePrefetcher(Delegate* delegate,
-                     const ResourcePrefetchPredictorConfig& config,
-                     const NavigationID& navigation_id,
-                     PrefetchKeyType key_type,
-                     scoped_ptr<RequestVector> requests);
-  virtual ~ResourcePrefetcher();
-
-  void Start();  // Kicks off the prefetching. Can only be called once.
-  void Stop();   // No additional prefetches will be queued after this.
-
-  const NavigationID& navigation_id() const { return navigation_id_; }
-  PrefetchKeyType key_type() const { return key_type_; }
-
- private:
-  friend class ResourcePrefetcherTest;
-  friend class TestResourcePrefetcher;
-
-  // Launches new prefetch requests if possible.
-  void TryToLaunchPrefetchRequests();
-
-  // Starts a net::URLRequest for the input |request|.
-  void SendRequest(Request* request);
-
-  // Called by |SendRequest| to start the |request|. This is necessary to stub
-  // out the Start() call to net::URLRequest for unittesting.
-  virtual void StartURLRequest(net::URLRequest* request);
-
-  // Marks the request as finished, with the given status.
-  void FinishRequest(net::URLRequest* request, Request::PrefetchStatus status);
-
-  // Reads the response data from the response - required for the resource to
-  // be cached correctly. Stubbed out during testing.
-  virtual void ReadFullResponse(net::URLRequest* request);
-
-  // Returns true if the request has more data that needs to be read. If it
-  // returns false, the request should not be referenced again.
-  bool ShouldContinueReadingRequest(net::URLRequest* request, int bytes_read);
-
-  // net::URLRequest::Delegate methods.
-  virtual void OnReceivedRedirect(net::URLRequest* request,
-                                  const net::RedirectInfo& redirect_info,
-                                  bool* defer_redirect) OVERRIDE;
-  virtual void OnAuthRequired(net::URLRequest* request,
-                              net::AuthChallengeInfo* auth_info) OVERRIDE;
-  virtual void OnCertificateRequested(
-      net::URLRequest* request,
-      net::SSLCertRequestInfo* cert_request_info) OVERRIDE;
-  virtual void OnSSLCertificateError(net::URLRequest* request,
-                                     const net::SSLInfo& ssl_info,
-                                     bool fatal) OVERRIDE;
-  virtual void OnResponseStarted(net::URLRequest* request) OVERRIDE;
-  virtual void OnReadCompleted(net::URLRequest* request,
-                               int bytes_read) OVERRIDE;
-
-  enum PrefetcherState {
-    INITIALIZED = 0,  // Prefetching hasn't started.
-    RUNNING = 1,      // Prefetching started, allowed to add more requests.
-    STOPPED = 2,      // Prefetching started, not allowed to add more requests.
-    FINISHED = 3      // No more inflight request, new requests not possible.
-  };
-
-  base::ThreadChecker thread_checker_;
-  PrefetcherState state_;
-  Delegate* const delegate_;
-  ResourcePrefetchPredictorConfig const config_;
-  NavigationID navigation_id_;
-  PrefetchKeyType key_type_;
-  scoped_ptr<RequestVector> request_vector_;
-
-  std::map<net::URLRequest*, Request*> inflight_requests_;
-  std::list<Request*> request_queue_;
-  std::map<std::string, size_t> host_inflight_counts_;
-
-  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcher);
-};
-
-}  // namespace predictors
-
-#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_