chrome/browser/prerender/prerender_local_predictor.h - chromium/src - Git at Google

 // 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.

 #ifndef CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_

 #include <map>
 #include <vector>

 #include "base/containers/hash_tables.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/history/visit_database.h"
 #include "content/public/browser/session_storage_namespace.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "url/gurl.h"

 class HistoryService;

 namespace base {
 class DictionaryValue;
 }

 namespace content {
 class WebContents;
 }

 namespace gfx {
 class Size;
 }

 namespace prerender {

 class PrerenderHandle;
 class PrerenderManager;

 // PrerenderLocalPredictor maintains local browsing history to make prerender
 // predictions.
 // At this point, the class is not actually creating prerenders, but just
 // recording timing stats about the effect prerendering would have.
 class PrerenderLocalPredictor : public history::VisitDatabaseObserver,
                                 public net::URLFetcherDelegate {
  public:
   struct LocalPredictorURLInfo;
   struct CandidatePrerenderInfo;
   // A class simulating a set of URLs prefetched, for statistical purposes.
   class PrefetchList;
   enum Event {
     EVENT_CONSTRUCTED = 0,
     EVENT_INIT_SCHEDULED = 1,
     EVENT_INIT_STARTED = 2,
     EVENT_INIT_FAILED_NO_HISTORY = 3,
     EVENT_INIT_SUCCEEDED = 4,
     EVENT_ADD_VISIT = 5,
     EVENT_ADD_VISIT_INITIALIZED = 6,
     EVENT_ADD_VISIT_PRERENDER_IDENTIFIED = 7,
     EVENT_ADD_VISIT_RELEVANT_TRANSITION = 8,
     EVENT_ADD_VISIT_IDENTIFIED_PRERENDER_CANDIDATE = 9,
     EVENT_ADD_VISIT_PRERENDERING = 10,
     EVENT_GOT_PRERENDER_URL = 11,
     EVENT_ERROR_NO_PRERENDER_URL_FOR_PLT = 12,
     EVENT_ADD_VISIT_PRERENDERING_EXTENDED = 13,
     EVENT_PRERENDER_URL_LOOKUP_RESULT = 14,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE = 15,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_IS_HTTP = 16,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_HAS_QUERY_STRING = 17,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGOUT = 18,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGIN = 19,
     EVENT_START_URL_LOOKUP = 20,
     EVENT_ADD_VISIT_NOT_ROOTPAGE = 21,
     EVENT_URL_WHITELIST_ERROR = 22,
     EVENT_URL_WHITELIST_OK = 23,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST = 24,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST_ROOT_PAGE = 25,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_EXTENDED_ROOT_PAGE = 26,
     EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE_HTTP = 27,
     EVENT_PRERENDER_URL_LOOKUP_FAILED = 28,
     EVENT_PRERENDER_URL_LOOKUP_NO_SOURCE_WEBCONTENTS_FOUND = 29,
     EVENT_PRERENDER_URL_LOOKUP_NO_LOGGED_IN_TABLE_FOUND = 30,
     EVENT_PRERENDER_URL_LOOKUP_ISSUING_LOGGED_IN_LOOKUP = 31,
     EVENT_CONTINUE_PRERENDER_CHECK_STARTED = 32,
     EVENT_CONTINUE_PRERENDER_CHECK_NO_URL = 33,
     EVENT_CONTINUE_PRERENDER_CHECK_PRIORITY_TOO_LOW = 34,
     EVENT_CONTINUE_PRERENDER_CHECK_URLS_IDENTICAL_BUT_FRAGMENT = 35,
     EVENT_CONTINUE_PRERENDER_CHECK_HTTPS = 36,
     EVENT_CONTINUE_PRERENDER_CHECK_ROOT_PAGE = 37,
     EVENT_CONTINUE_PRERENDER_CHECK_LOGOUT_URL = 38,
     EVENT_CONTINUE_PRERENDER_CHECK_LOGIN_URL = 39,
     EVENT_CONTINUE_PRERENDER_CHECK_NOT_LOGGED_IN = 40,
     EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_NOT_PRERENDERING = 41,
     EVENT_CONTINUE_PRERENDER_CHECK_ISSUING_PRERENDER = 42,
     EVENT_ISSUING_PRERENDER = 43,
     EVENT_NO_PRERENDER_CANDIDATES = 44,
     EVENT_GOT_HISTORY_ISSUING_LOOKUP = 45,
     EVENT_TAB_HELPER_URL_SEEN = 46,
     EVENT_TAB_HELPER_URL_SEEN_MATCH = 47,
     EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH = 48,
     EVENT_PRERENDER_URL_LOOKUP_MULTIPLE_SOURCE_WEBCONTENTS_FOUND = 49,
     EVENT_CONTINUE_PRERENDER_CHECK_ON_SIDE_EFFECT_FREE_WHITELIST = 50,
     EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL = 51,
     EVENT_ISSUE_PRERENDER_ALREADY_PRERENDERING = 52,
     EVENT_ISSUE_PRERENDER_NEW_PRERENDER = 53,
     EVENT_ISSUE_PRERENDER_CANCELLED_OLD_PRERENDER = 54,
     EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_PRERENDERING = 55,
     EVENT_PRERENDER_URL_LOOKUP_SUCCESS = 56,
     EVENT_PRERENDER_SERVICE_DISABLED = 57,
     EVENT_PRERENDER_SERVICE_ISSUED_LOOKUP = 58,
     EVENT_PRERENDER_SERVICE_LOOKUP_TIMED_OUT = 59,
     EVENT_PRERENDER_SERVICE_RECEIVED_RESULT = 60,
     EVENT_PRERENDER_SERVICE_NO_RECORD_FOR_RESULT = 61,
     EVENT_PRERENDER_SERVICE_PARSED_CORRECTLY = 62,
     EVENT_PRERENDER_SERVICE_PARSE_ERROR = 63,
     EVENT_PRERENDER_SERVICE_PARSE_ERROR_INCORRECT_JSON = 64,
     EVENT_PRERENDER_SERVICE_HINTING_TIMED_OUT = 65,
     EVENT_PRERENDER_SERVICE_HINTING_URL_LOOKUP_TIMED_OUT = 66,
     EVENT_PRERENDER_SERVICE_CANDIDATE_URL_LOOKUP_TIMED_OUT = 67,
     EVENT_CONTINUE_PRERENDER_CHECK_ON_SERVICE_WHITELIST = 68,
     EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_LOCAL = 69,
     EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_SERVICE = 70,
     EVENT_ADD_VISIT_RELEVANT_TRANSITION_REPEAT_URL = 71,
     EVENT_ADD_VISIT_RELEVANT_TRANSITION_NEW_URL = 72,
     EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MISMATCH_NO_NAMESPACE = 73,
     EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MISMATCH_MERGE_ISSUED = 74,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_RECEIVED = 75,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NAMESPACE_NOT_FOUND = 76,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NOT_LOGGING = 77,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NO_TRANSACTIONS = 78,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_TOO_MANY_TRANSACTIONS = 79,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NOT_MERGEABLE = 80,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_MERGEABLE = 81,
     EVENT_INIT_FAILED_UNENCRYPTED_SYNC_NOT_ENABLED = 82,
     EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_NOT_SKIPPED = 83,
     EVENT_PRERENDER_SERVICE_RETURNED_HINTING_CANDIDATES = 84,
     EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NAMESPACE_NOT_ALIAS = 85,
     EVENT_TAB_HELPER_URL_SEEN_MATCH_ENTRY = 86,
     EVENT_TAB_HELPER_URL_SEEN_MATCH_BROWSER_NAVIGATE = 87,
     EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_ENTRY = 88,
     EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_BROWSER_NAVIGATE = 89,
     EVENT_PREFETCH_LIST_ADDED = 90,
     EVENT_PREFETCH_LIST_SEEN_TABCONTENTS = 91,
     EVENT_PREFETCH_LIST_SEEN_HISTORY = 92,
     EVENT_ISSUE_PRERENDER_CALLED = 93,
     EVENT_ISSUE_PRERENDER_PREFETCH_ENABLED = 94,
     EVENT_ISSUE_PRERENDER_PREFETCH_ISSUED = 95,
     EVENT_MAX_VALUE
   };

   // A PrerenderLocalPredictor is owned by the PrerenderManager specified
   // in the constructor.  It will be destoryed at the time its owning
   // PrerenderManager is destroyed.
   explicit PrerenderLocalPredictor(PrerenderManager* prerender_manager);
   virtual ~PrerenderLocalPredictor();

   void Shutdown();

   // history::VisitDatabaseObserver implementation
   virtual void OnAddVisit(const history::BriefVisitInfo& info) override;

   void OnGetInitialVisitHistory(
       scoped_ptr<std::vector<history::BriefVisitInfo> > visit_history);

   void OnPLTEventForURL(const GURL& url, base::TimeDelta page_load_time);

   void OnTabHelperURLSeen(const GURL& url, content::WebContents* web_contents);

   // net::URLFetcherDelegate implementation:
   void virtual OnURLFetchComplete(const net::URLFetcher* source) override;

  private:
   struct PrerenderProperties;
   HistoryService* GetHistoryIfExists() const;
   void Init();
   bool IsPrerenderStillValid(PrerenderProperties* prerender) const;
   bool DoesPrerenderMatchPLTRecord(PrerenderProperties* prerender,
                                    const GURL& url,
                                    base::TimeDelta plt) const;
   void RecordEvent(Event event) const;

   void OnLookupURL(scoped_ptr<CandidatePrerenderInfo> info);

   // Lookup the prerender candidate in the Prerender Service (if applicable).
   void DoPrerenderServiceCheck(scoped_ptr<CandidatePrerenderInfo> info);

   // Lookup the prerender candidate in the LoggedIn Predictor.
   void DoLoggedInLookup(scoped_ptr<CandidatePrerenderInfo> info);

   // Returns an element of issued_prerenders_, which should be replaced
   // by a new prerender of the priority indicated, or NULL, if the priority
   // is too low (or if the URL requested is already prerendering).
   PrerenderProperties* GetIssuedPrerenderSlotForPriority(const GURL& url,
                                                          double priority);

   void ContinuePrerenderCheck(scoped_ptr<CandidatePrerenderInfo> info);
   void LogCandidateURLStats(const GURL& url) const;
   void IssuePrerender(CandidatePrerenderInfo* info,
                       LocalPredictorURLInfo* url_info);
   void MaybeCancelURLFetcher(net::URLFetcher* fetcher);
   // Returns true if the parsed response is semantically correct and could
   // be fully applied.
   bool ApplyParsedPrerenderServiceResponse(
       base::DictionaryValue* dict,
       CandidatePrerenderInfo* info,
       bool* hinting_timed_out,
       bool* hinting_url_lookup_timed_out,
       bool* candidate_url_lookup_timed_out);
   void ProcessNamespaceMergeResult(
       content::SessionStorageNamespace::MergeResult result);
   typedef std::map<net::URLFetcher*, CandidatePrerenderInfo*>
       OutstandingFetchers;
   OutstandingFetchers outstanding_prerender_service_requests_;
   PrerenderManager* prerender_manager_;
   base::OneShotTimer<PrerenderLocalPredictor> timer_;

   // Delay after which to initialize, to avoid putting to much load on the
   // database thread early on when Chrome is starting up.
   static const int kInitDelayMs = 5 * 1000;

   // Whether we're registered with the history service as a
   // history::VisitDatabaseObserver.
   bool is_visit_database_observer_;

   base::CancelableTaskTracker history_db_tracker_;

   scoped_ptr<std::vector<history::BriefVisitInfo> > visit_history_;

   scoped_ptr<PrerenderProperties> current_prerender_;
   scoped_ptr<PrerenderProperties> last_swapped_in_prerender_;

   ScopedVector<PrerenderProperties> issued_prerenders_;

   base::hash_set<int64> url_whitelist_;

   base::WeakPtrFactory<PrerenderLocalPredictor> weak_factory_;

   scoped_ptr<PrefetchList> prefetch_list_;

   DISALLOW_COPY_AND_ASSIGN(PrerenderLocalPredictor);
 };

 }  // namespace prerender

 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_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.

	#ifndef CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_
	#define CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_

	#include <map>
	#include <vector>

	#include "base/containers/hash_tables.h"
	#include "base/memory/scoped_vector.h"
	#include "base/memory/weak_ptr.h"
	#include "base/task/cancelable_task_tracker.h"
	#include "base/timer/timer.h"
	#include "chrome/browser/history/visit_database.h"
	#include "content/public/browser/session_storage_namespace.h"
	#include "net/url_request/url_fetcher_delegate.h"
	#include "url/gurl.h"

	class HistoryService;

	namespace base {
	class DictionaryValue;
	}

	namespace content {
	class WebContents;
	}

	namespace gfx {
	class Size;
	}

	namespace prerender {

	class PrerenderHandle;
	class PrerenderManager;

	// PrerenderLocalPredictor maintains local browsing history to make prerender
	// predictions.
	// At this point, the class is not actually creating prerenders, but just
	// recording timing stats about the effect prerendering would have.
	class PrerenderLocalPredictor : public history::VisitDatabaseObserver,
	public net::URLFetcherDelegate {
	public:
	struct LocalPredictorURLInfo;
	struct CandidatePrerenderInfo;
	// A class simulating a set of URLs prefetched, for statistical purposes.
	class PrefetchList;
	enum Event {
	EVENT_CONSTRUCTED = 0,
	EVENT_INIT_SCHEDULED = 1,
	EVENT_INIT_STARTED = 2,
	EVENT_INIT_FAILED_NO_HISTORY = 3,
	EVENT_INIT_SUCCEEDED = 4,
	EVENT_ADD_VISIT = 5,
	EVENT_ADD_VISIT_INITIALIZED = 6,
	EVENT_ADD_VISIT_PRERENDER_IDENTIFIED = 7,
	EVENT_ADD_VISIT_RELEVANT_TRANSITION = 8,
	EVENT_ADD_VISIT_IDENTIFIED_PRERENDER_CANDIDATE = 9,
	EVENT_ADD_VISIT_PRERENDERING = 10,
	EVENT_GOT_PRERENDER_URL = 11,
	EVENT_ERROR_NO_PRERENDER_URL_FOR_PLT = 12,
	EVENT_ADD_VISIT_PRERENDERING_EXTENDED = 13,
	EVENT_PRERENDER_URL_LOOKUP_RESULT = 14,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE = 15,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_IS_HTTP = 16,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_HAS_QUERY_STRING = 17,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGOUT = 18,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGIN = 19,
	EVENT_START_URL_LOOKUP = 20,
	EVENT_ADD_VISIT_NOT_ROOTPAGE = 21,
	EVENT_URL_WHITELIST_ERROR = 22,
	EVENT_URL_WHITELIST_OK = 23,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST = 24,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST_ROOT_PAGE = 25,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_EXTENDED_ROOT_PAGE = 26,
	EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE_HTTP = 27,
	EVENT_PRERENDER_URL_LOOKUP_FAILED = 28,
	EVENT_PRERENDER_URL_LOOKUP_NO_SOURCE_WEBCONTENTS_FOUND = 29,
	EVENT_PRERENDER_URL_LOOKUP_NO_LOGGED_IN_TABLE_FOUND = 30,
	EVENT_PRERENDER_URL_LOOKUP_ISSUING_LOGGED_IN_LOOKUP = 31,
	EVENT_CONTINUE_PRERENDER_CHECK_STARTED = 32,
	EVENT_CONTINUE_PRERENDER_CHECK_NO_URL = 33,
	EVENT_CONTINUE_PRERENDER_CHECK_PRIORITY_TOO_LOW = 34,
	EVENT_CONTINUE_PRERENDER_CHECK_URLS_IDENTICAL_BUT_FRAGMENT = 35,
	EVENT_CONTINUE_PRERENDER_CHECK_HTTPS = 36,
	EVENT_CONTINUE_PRERENDER_CHECK_ROOT_PAGE = 37,
	EVENT_CONTINUE_PRERENDER_CHECK_LOGOUT_URL = 38,
	EVENT_CONTINUE_PRERENDER_CHECK_LOGIN_URL = 39,
	EVENT_CONTINUE_PRERENDER_CHECK_NOT_LOGGED_IN = 40,
	EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_NOT_PRERENDERING = 41,
	EVENT_CONTINUE_PRERENDER_CHECK_ISSUING_PRERENDER = 42,
	EVENT_ISSUING_PRERENDER = 43,
	EVENT_NO_PRERENDER_CANDIDATES = 44,
	EVENT_GOT_HISTORY_ISSUING_LOOKUP = 45,
	EVENT_TAB_HELPER_URL_SEEN = 46,
	EVENT_TAB_HELPER_URL_SEEN_MATCH = 47,
	EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH = 48,
	EVENT_PRERENDER_URL_LOOKUP_MULTIPLE_SOURCE_WEBCONTENTS_FOUND = 49,
	EVENT_CONTINUE_PRERENDER_CHECK_ON_SIDE_EFFECT_FREE_WHITELIST = 50,
	EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL = 51,
	EVENT_ISSUE_PRERENDER_ALREADY_PRERENDERING = 52,
	EVENT_ISSUE_PRERENDER_NEW_PRERENDER = 53,
	EVENT_ISSUE_PRERENDER_CANCELLED_OLD_PRERENDER = 54,
	EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_PRERENDERING = 55,
	EVENT_PRERENDER_URL_LOOKUP_SUCCESS = 56,
	EVENT_PRERENDER_SERVICE_DISABLED = 57,
	EVENT_PRERENDER_SERVICE_ISSUED_LOOKUP = 58,
	EVENT_PRERENDER_SERVICE_LOOKUP_TIMED_OUT = 59,
	EVENT_PRERENDER_SERVICE_RECEIVED_RESULT = 60,
	EVENT_PRERENDER_SERVICE_NO_RECORD_FOR_RESULT = 61,
	EVENT_PRERENDER_SERVICE_PARSED_CORRECTLY = 62,
	EVENT_PRERENDER_SERVICE_PARSE_ERROR = 63,
	EVENT_PRERENDER_SERVICE_PARSE_ERROR_INCORRECT_JSON = 64,
	EVENT_PRERENDER_SERVICE_HINTING_TIMED_OUT = 65,
	EVENT_PRERENDER_SERVICE_HINTING_URL_LOOKUP_TIMED_OUT = 66,
	EVENT_PRERENDER_SERVICE_CANDIDATE_URL_LOOKUP_TIMED_OUT = 67,
	EVENT_CONTINUE_PRERENDER_CHECK_ON_SERVICE_WHITELIST = 68,
	EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_LOCAL = 69,
	EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_SERVICE = 70,
	EVENT_ADD_VISIT_RELEVANT_TRANSITION_REPEAT_URL = 71,
	EVENT_ADD_VISIT_RELEVANT_TRANSITION_NEW_URL = 72,
	EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MISMATCH_NO_NAMESPACE = 73,
	EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MISMATCH_MERGE_ISSUED = 74,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_RECEIVED = 75,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NAMESPACE_NOT_FOUND = 76,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NOT_LOGGING = 77,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NO_TRANSACTIONS = 78,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_TOO_MANY_TRANSACTIONS = 79,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NOT_MERGEABLE = 80,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_MERGEABLE = 81,
	EVENT_INIT_FAILED_UNENCRYPTED_SYNC_NOT_ENABLED = 82,
	EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_NOT_SKIPPED = 83,
	EVENT_PRERENDER_SERVICE_RETURNED_HINTING_CANDIDATES = 84,
	EVENT_NAMESPACE_MISMATCH_MERGE_RESULT_NAMESPACE_NOT_ALIAS = 85,
	EVENT_TAB_HELPER_URL_SEEN_MATCH_ENTRY = 86,
	EVENT_TAB_HELPER_URL_SEEN_MATCH_BROWSER_NAVIGATE = 87,
	EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_ENTRY = 88,
	EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_BROWSER_NAVIGATE = 89,
	EVENT_PREFETCH_LIST_ADDED = 90,
	EVENT_PREFETCH_LIST_SEEN_TABCONTENTS = 91,
	EVENT_PREFETCH_LIST_SEEN_HISTORY = 92,
	EVENT_ISSUE_PRERENDER_CALLED = 93,
	EVENT_ISSUE_PRERENDER_PREFETCH_ENABLED = 94,
	EVENT_ISSUE_PRERENDER_PREFETCH_ISSUED = 95,
	EVENT_MAX_VALUE
	};

	// A PrerenderLocalPredictor is owned by the PrerenderManager specified
	// in the constructor. It will be destoryed at the time its owning
	// PrerenderManager is destroyed.
	explicit PrerenderLocalPredictor(PrerenderManager* prerender_manager);
	virtual ~PrerenderLocalPredictor();

	void Shutdown();

	// history::VisitDatabaseObserver implementation
	virtual void OnAddVisit(const history::BriefVisitInfo& info) override;

	void OnGetInitialVisitHistory(
	scoped_ptr<std::vector<history::BriefVisitInfo> > visit_history);

	void OnPLTEventForURL(const GURL& url, base::TimeDelta page_load_time);

	void OnTabHelperURLSeen(const GURL& url, content::WebContents* web_contents);

	// net::URLFetcherDelegate implementation:
	void virtual OnURLFetchComplete(const net::URLFetcher* source) override;

	private:
	struct PrerenderProperties;
	HistoryService* GetHistoryIfExists() const;
	void Init();
	bool IsPrerenderStillValid(PrerenderProperties* prerender) const;
	bool DoesPrerenderMatchPLTRecord(PrerenderProperties* prerender,
	const GURL& url,
	base::TimeDelta plt) const;
	void RecordEvent(Event event) const;

	void OnLookupURL(scoped_ptr<CandidatePrerenderInfo> info);

	// Lookup the prerender candidate in the Prerender Service (if applicable).
	void DoPrerenderServiceCheck(scoped_ptr<CandidatePrerenderInfo> info);

	// Lookup the prerender candidate in the LoggedIn Predictor.
	void DoLoggedInLookup(scoped_ptr<CandidatePrerenderInfo> info);

	// Returns an element of issued_prerenders_, which should be replaced
	// by a new prerender of the priority indicated, or NULL, if the priority
	// is too low (or if the URL requested is already prerendering).
	PrerenderProperties* GetIssuedPrerenderSlotForPriority(const GURL& url,
	double priority);

	void ContinuePrerenderCheck(scoped_ptr<CandidatePrerenderInfo> info);
	void LogCandidateURLStats(const GURL& url) const;
	void IssuePrerender(CandidatePrerenderInfo* info,
	LocalPredictorURLInfo* url_info);
	void MaybeCancelURLFetcher(net::URLFetcher* fetcher);
	// Returns true if the parsed response is semantically correct and could
	// be fully applied.
	bool ApplyParsedPrerenderServiceResponse(
	base::DictionaryValue* dict,
	CandidatePrerenderInfo* info,
	bool* hinting_timed_out,
	bool* hinting_url_lookup_timed_out,
	bool* candidate_url_lookup_timed_out);
	void ProcessNamespaceMergeResult(
	content::SessionStorageNamespace::MergeResult result);
	typedef std::map<net::URLFetcher, CandidatePrerenderInfo>
	OutstandingFetchers;
	OutstandingFetchers outstanding_prerender_service_requests_;
	PrerenderManager* prerender_manager_;
	base::OneShotTimer<PrerenderLocalPredictor> timer_;

	// Delay after which to initialize, to avoid putting to much load on the
	// database thread early on when Chrome is starting up.
	static const int kInitDelayMs = 5 * 1000;

	// Whether we're registered with the history service as a
	// history::VisitDatabaseObserver.
	bool is_visit_database_observer_;

	base::CancelableTaskTracker history_db_tracker_;

	scoped_ptr<std::vector<history::BriefVisitInfo> > visit_history_;

	scoped_ptr<PrerenderProperties> current_prerender_;
	scoped_ptr<PrerenderProperties> last_swapped_in_prerender_;

	ScopedVector<PrerenderProperties> issued_prerenders_;

	base::hash_set<int64> url_whitelist_;

	base::WeakPtrFactory<PrerenderLocalPredictor> weak_factory_;

	scoped_ptr<PrefetchList> prefetch_list_;

	DISALLOW_COPY_AND_ASSIGN(PrerenderLocalPredictor);
	};

	} // namespace prerender

	#endif // CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_