Remove PrerenderLocalPredictor, part 1.

chrome/browser/prerender/prerender_local_predictor.cc

Index: chrome/browser/prerender/prerender_local_predictor.cc
diff --git a/chrome/browser/prerender/prerender_local_predictor.cc b/chrome/browser/prerender/prerender_local_predictor.cc
deleted file mode 100644
index 671ba32072627c3f6af9bc8c61a18bb1fc29b7e7..0000000000000000000000000000000000000000
--- a/chrome/browser/prerender/prerender_local_predictor.cc
+++ /dev/null
@@ -1,1531 +0,0 @@
-// 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.
-
-#include "chrome/browser/prerender/prerender_local_predictor.h"
-
-#include <ctype.h>
-
-#include <algorithm>
-#include <map>
-#include <set>
-#include <string>
-#include <utility>
-
-#include "base/json/json_reader.h"
-#include "base/json/json_writer.h"
-#include "base/metrics/field_trial.h"
-#include "base/metrics/histogram.h"
-#include "base/stl_util.h"
-#include "base/timer/timer.h"
-#include "chrome/browser/browser_process.h"
-#include "chrome/browser/history/history_service_factory.h"
-#include "chrome/browser/prerender/prerender_field_trial.h"
-#include "chrome/browser/prerender/prerender_handle.h"
-#include "chrome/browser/prerender/prerender_histograms.h"
-#include "chrome/browser/prerender/prerender_manager.h"
-#include "chrome/browser/prerender/prerender_util.h"
-#include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/safe_browsing/database_manager.h"
-#include "chrome/browser/safe_browsing/safe_browsing_service.h"
-#include "chrome/browser/ui/tab_contents/tab_contents_iterator.h"
-#include "chrome/common/prefetch_messages.h"
-#include "components/history/core/browser/history_database.h"
-#include "components/history/core/browser/history_db_task.h"
-#include "components/history/core/browser/history_service.h"
-#include "content/public/browser/browser_thread.h"
-#include "content/public/browser/navigation_controller.h"
-#include "content/public/browser/navigation_entry.h"
-#include "content/public/browser/render_frame_host.h"
-#include "content/public/browser/render_process_host.h"
-#include "content/public/browser/web_contents.h"
-#include "crypto/secure_hash.h"
-#include "grit/browser_resources.h"
-#include "net/base/escape.h"
-#include "net/base/load_flags.h"
-#include "net/url_request/url_fetcher.h"
-#include "ui/base/page_transition_types.h"
-#include "ui/base/resource/resource_bundle.h"
-#include "url/url_canon.h"
-
-using base::DictionaryValue;
-using base::ListValue;
-using base::Value;
-using content::BrowserThread;
-using ui::PageTransition;
-using content::RenderFrameHost;
-using content::SessionStorageNamespace;
-using content::WebContents;
-using history::URLID;
-using net::URLFetcher;
-using predictors::LoggedInPredictorTable;
-using std::string;
-using std::vector;
-
-namespace prerender {
-
-namespace {
-
-static const size_t kURLHashSize = 5;
-static const int kNumPrerenderCandidates = 5;
-static const int kInvalidProcessId = -1;
-static const int kInvalidFrameId = -1;
-static const int kMaxPrefetchItems = 100;
-
-}  // namespace
-
-// When considering a candidate URL to be prerendered, we need to collect the
-// data in this struct to make the determination whether we should issue the
-// prerender or not.
-struct PrerenderLocalPredictor::LocalPredictorURLInfo {
-  URLID id;
-  GURL url;
-  bool url_lookup_success;
-  bool logged_in;
-  bool logged_in_lookup_ok;
-  bool local_history_based;
-  bool service_whitelist;
-  bool service_whitelist_lookup_ok;
-  bool service_whitelist_reported;
-  double priority;
-};
-
-// A struct consisting of everything needed for launching a potential prerender
-// on a navigation: The navigation URL (source) triggering potential prerenders,
-// and a set of candidate URLs.
-struct PrerenderLocalPredictor::CandidatePrerenderInfo {
-  LocalPredictorURLInfo source_url_;
-  vector<LocalPredictorURLInfo> candidate_urls_;
-  scoped_refptr<SessionStorageNamespace> session_storage_namespace_;
-  // Render Process ID and Route ID of the page causing the prerender to be
-  // issued. Needed so that we can cause its renderer to issue prefetches within
-  // its context.
-  int render_process_id_;
-  int render_frame_id_;
-  scoped_ptr<gfx::Size> size_;
-  base::Time start_time_;  // used for various time measurements
-  explicit CandidatePrerenderInfo(URLID source_id)
-      : render_process_id_(kInvalidProcessId),
-        render_frame_id_(kInvalidFrameId) {
-    source_url_.id = source_id;
-  }
-  void MaybeAddCandidateURLFromLocalData(URLID id, double priority) {
-    LocalPredictorURLInfo info;
-    info.id = id;
-    info.local_history_based = true;
-    info.service_whitelist = false;
-    info.service_whitelist_lookup_ok = false;
-    info.service_whitelist_reported = false;
-    info.priority = priority;
-    MaybeAddCandidateURLInternal(info);
-  }
-  void MaybeAddCandidateURLFromService(GURL url, double priority,
-                                       bool whitelist,
-                                       bool whitelist_lookup_ok) {
-    LocalPredictorURLInfo info;
-    info.id = kint64max;
-    info.url = url;
-    info.url_lookup_success = true;
-    info.local_history_based = false;
-    info.service_whitelist = whitelist;
-    info.service_whitelist_lookup_ok = whitelist_lookup_ok;
-    info.service_whitelist_reported = true;
-    info.priority = priority;
-    MaybeAddCandidateURLInternal(info);
-  }
-  void MaybeAddCandidateURLInternal(const LocalPredictorURLInfo& info) {
-    // TODO(tburkard): clean up this code, potentially using a list or a heap
-    int max_candidates = kNumPrerenderCandidates;
-    // We first insert local candidates, then service candidates.
-    // Since we want to keep kNumPrerenderCandidates for both local & service
-    // candidates, we need to double the maximum number of candidates once
-    // we start seeing service candidates.
-    if (!info.local_history_based)
-      max_candidates *= 2;
-    int insert_pos = candidate_urls_.size();
-    if (insert_pos < max_candidates)
-      candidate_urls_.push_back(info);
-    while (insert_pos > 0 &&
-           candidate_urls_[insert_pos - 1].priority < info.priority) {
-      if (insert_pos < max_candidates)
-        candidate_urls_[insert_pos] = candidate_urls_[insert_pos - 1];
-      insert_pos--;
-    }
-    if (insert_pos < max_candidates)
-      candidate_urls_[insert_pos] = info;
-  }
-};
-
-namespace {
-
-#define TIMING_HISTOGRAM(name, value)                               \
-  UMA_HISTOGRAM_CUSTOM_TIMES(name, value,                           \
-                             base::TimeDelta::FromMilliseconds(10), \
-                             base::TimeDelta::FromSeconds(10),      \
-                             50);
-
-// Task to lookup the URL for a given URLID.
-class GetURLForURLIDTask : public history::HistoryDBTask {
- public:
-  GetURLForURLIDTask(
-      PrerenderLocalPredictor::CandidatePrerenderInfo* request,
-      const base::Closure& callback)
-      : request_(request),
-        callback_(callback),
-        start_time_(base::Time::Now()) {
-  }
-
-  bool RunOnDBThread(history::HistoryBackend* backend,
-                     history::HistoryDatabase* db) override {
-    DoURLLookup(db, &request_->source_url_);
-    for (int i = 0; i < static_cast<int>(request_->candidate_urls_.size()); i++)
-      DoURLLookup(db, &request_->candidate_urls_[i]);
-    return true;
-  }
-
-  void DoneRunOnMainThread() override {
-    callback_.Run();
-    TIMING_HISTOGRAM("Prerender.LocalPredictorURLLookupTime",
-                     base::Time::Now() - start_time_);

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done. (Also seems worth having tooling, though I should haven't remembered
this.)

-  }
-
- private:
-  ~GetURLForURLIDTask() override {}
-
-  void DoURLLookup(history::HistoryDatabase* db,
-                   PrerenderLocalPredictor::LocalPredictorURLInfo* request) {
-    history::URLRow url_row;
-    request->url_lookup_success = db->GetURLRow(request->id, &url_row);
-    if (request->url_lookup_success)
-      request->url = url_row.url();
-  }
-
-  PrerenderLocalPredictor::CandidatePrerenderInfo* request_;
-  base::Closure callback_;
-  base::Time start_time_;
-  DISALLOW_COPY_AND_ASSIGN(GetURLForURLIDTask);
-};
-
-// Task to load history from the visit database on startup.
-class GetVisitHistoryTask : public history::HistoryDBTask {
- public:
-  GetVisitHistoryTask(PrerenderLocalPredictor* local_predictor,
-                      int max_visits)
-      : local_predictor_(local_predictor),
-        max_visits_(max_visits),
-        visit_history_(new vector<history::BriefVisitInfo>) {
-  }
-
-  bool RunOnDBThread(history::HistoryBackend* backend,
-                     history::HistoryDatabase* db) override {
-    db->GetBriefVisitInfoOfMostRecentVisits(max_visits_, visit_history_.get());

[mmenke, 2015/04/10 16:42:04]

In fact, I think this is the only reason BriefVisitInfo even exists?  Rip it all
out?  Fine to do in another CL.

[mmenke, 2015/04/10 16:42:04]

This class is the only consumer of this method.  Remove it, too?

[davidben, 2015/04/13 15:51:14]

Good catch. I'll do that in a follow-up.

[davidben, 2015/04/13 16:40:01]

(For posterity, here's that follow-up.
https://codereview.chromium.org/1081923002/ )

-    return true;
-  }
-
-  void DoneRunOnMainThread() override {
-    local_predictor_->OnGetInitialVisitHistory(visit_history_.Pass());
-  }
-
- private:
-  ~GetVisitHistoryTask() override {}
-
-  PrerenderLocalPredictor* local_predictor_;
-  int max_visits_;
-  scoped_ptr<vector<history::BriefVisitInfo> > visit_history_;
-  DISALLOW_COPY_AND_ASSIGN(GetVisitHistoryTask);
-};
-
-// Maximum visit history to retrieve from the visit database.
-const int kMaxVisitHistory = 100 * 1000;
-
-// Visit history size at which to trigger pruning, and number of items to prune.
-const int kVisitHistoryPruneThreshold = 120 * 1000;
-const int kVisitHistoryPruneAmount = 20 * 1000;
-
-const int kMinLocalPredictionTimeMs = 500;
-
-int GetMaxLocalPredictionTimeMs() {
-  return GetLocalPredictorTTLSeconds() * 1000;
-}
-
-bool IsBackForward(PageTransition transition) {
-  return (transition & ui::PAGE_TRANSITION_FORWARD_BACK) != 0;
-}
-
-bool IsHomePage(PageTransition transition) {
-  return (transition & ui::PAGE_TRANSITION_HOME_PAGE) != 0;
-}
-
-bool IsIntermediateRedirect(PageTransition transition) {
-  return (transition & ui::PAGE_TRANSITION_CHAIN_END) == 0;
-}
-
-bool IsFormSubmit(PageTransition transition) {
-  return ui::PageTransitionCoreTypeIs(transition,
-                                      ui::PAGE_TRANSITION_FORM_SUBMIT);
-}
-
-bool ShouldExcludeTransitionForPrediction(PageTransition transition) {
-  return IsBackForward(transition) || IsHomePage(transition) ||
-      IsIntermediateRedirect(transition);
-}
-
-base::Time GetCurrentTime() {
-  return base::Time::Now();
-}
-
-bool StringContainsIgnoringCase(string haystack, string needle) {
-  std::transform(haystack.begin(), haystack.end(), haystack.begin(), ::tolower);
-  std::transform(needle.begin(), needle.end(), needle.begin(), ::tolower);
-  return haystack.find(needle) != string::npos;
-}
-
-bool IsExtendedRootURL(const GURL& url) {
-  const string& path = url.path();
-  return path == "/index.html" || path == "/home.html" ||
-      path == "/main.html" ||
-      path == "/index.htm" || path == "/home.htm" || path == "/main.htm" ||
-      path == "/index.php" || path == "/home.php" || path == "/main.php" ||
-      path == "/index.asp" || path == "/home.asp" || path == "/main.asp" ||
-      path == "/index.py" || path == "/home.py" || path == "/main.py" ||
-      path == "/index.pl" || path == "/home.pl" || path == "/main.pl";
-}
-
-bool IsRootPageURL(const GURL& url) {
-  return (url.path() == "/" || url.path().empty() || IsExtendedRootURL(url)) &&
-      (!url.has_query()) && (!url.has_ref());
-}
-
-bool IsLogInURL(const GURL& url) {
-  return StringContainsIgnoringCase(url.spec().c_str(), "login") ||
-      StringContainsIgnoringCase(url.spec().c_str(), "signin");
-}
-
-bool IsLogOutURL(const GURL& url) {
-  return StringContainsIgnoringCase(url.spec().c_str(), "logout") ||
-      StringContainsIgnoringCase(url.spec().c_str(), "signout");
-}
-
-int64 URLHashToInt64(const unsigned char* data) {
-  static_assert(kURLHashSize < sizeof(int64), "url hash must fit in int64");
-  int64 value = 0;
-  memcpy(&value, data, kURLHashSize);
-  return value;
-}
-
-int64 GetInt64URLHashForURL(const GURL& url) {
-  static_assert(kURLHashSize < sizeof(int64), "url hash must fit in int64");
-  scoped_ptr<crypto::SecureHash> hash(
-      crypto::SecureHash::Create(crypto::SecureHash::SHA256));
-  int64 hash_value = 0;
-  const char* url_string = url.spec().c_str();
-  hash->Update(url_string, strlen(url_string));
-  hash->Finish(&hash_value, kURLHashSize);
-  return hash_value;
-}
-
-bool URLsIdenticalIgnoringFragments(const GURL& url1, const GURL& url2) {
-  url::Replacements<char> replacement;
-  replacement.ClearRef();
-  GURL u1 = url1.ReplaceComponents(replacement);
-  GURL u2 = url2.ReplaceComponents(replacement);
-  return (u1 == u2);
-}
-
-void LookupLoggedInStatesOnDBThread(
-    scoped_refptr<LoggedInPredictorTable> logged_in_predictor_table,
-    PrerenderLocalPredictor::CandidatePrerenderInfo* request) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
-  for (int i = 0; i < static_cast<int>(request->candidate_urls_.size()); i++) {
-    PrerenderLocalPredictor::LocalPredictorURLInfo* info =
-        &request->candidate_urls_[i];
-    if (info->url_lookup_success) {
-      logged_in_predictor_table->HasUserLoggedIn(
-          info->url, &info->logged_in, &info->logged_in_lookup_ok);
-    } else {
-      info->logged_in_lookup_ok = false;
-    }
-  }
-}
-
-}  // namespace
-
-struct PrerenderLocalPredictor::PrerenderProperties {
-  PrerenderProperties(URLID url_id, const GURL& url, double priority,
-                base::Time start_time)
-      : url_id(url_id),
-        url(url),
-        priority(priority),
-        start_time(start_time),
-        would_have_matched(false) {
-  }
-
-  // Default constructor for dummy element
-  PrerenderProperties()
-      : priority(0.0), would_have_matched(false) {
-  }
-
-  double GetCurrentDecayedPriority() {
-    // If we are no longer prerendering, the priority is 0.
-    if (!prerender_handle || !prerender_handle->IsPrerendering())
-      return 0.0;
-    int half_life_time_seconds =
-        GetLocalPredictorPrerenderPriorityHalfLifeTimeSeconds();
-    if (half_life_time_seconds < 1)
-      return priority;
-    double multiple_elapsed =
-        (GetCurrentTime() - actual_start_time).InMillisecondsF() /
-        base::TimeDelta::FromSeconds(half_life_time_seconds).InMillisecondsF();
-    // Decay factor: 2 ^ (-multiple_elapsed)
-    double decay_factor = exp(- multiple_elapsed * log(2.0));
-    return priority * decay_factor;
-  }
-
-  URLID url_id;
-  GURL url;
-  double priority;
-  // For expiration purposes, this is a synthetic start time consisting either
-  // of the actual start time, or of the last time the page was re-requested
-  // for prerendering - 10 seconds (unless the original request came after
-  // that).  This is to emulate the effect of re-prerendering a page that is
-  // about to expire, because it was re-requested for prerendering a second
-  // time after the actual prerender being kept around.
-  base::Time start_time;
-  // The actual time this page was last requested for prerendering.
-  base::Time actual_start_time;
-  scoped_ptr<PrerenderHandle> prerender_handle;
-  // Indicates whether this prerender would have matched a URL navigated to,
-  // but was not swapped in for some reason.
-  bool would_have_matched;
-};
-
-// A class simulating a set of URLs prefetched, for statistical purposes.
-class PrerenderLocalPredictor::PrefetchList {
- public:
-  enum SeenType {
-    SEEN_TABCONTENTS_OBSERVER,
-    SEEN_HISTORY,
-    SEEN_MAX_VALUE
-  };
-
-  PrefetchList() {}
-  ~PrefetchList() {
-    STLDeleteValues(&entries_);
-  }
-
-  // Adds a new URL being prefetched. If the URL is already in the list,
-  // nothing will happen. Returns whether a new prefetch was added.
-  bool AddURL(const GURL& url) {
-    ExpireOldItems();
-    string url_string = url.spec().c_str();
-    base::hash_map<string, ListEntry*>::iterator it = entries_.find(url_string);
-    if (it != entries_.end()) {
-      // If a prefetch previously existed, and has not been seen yet in either
-      // a tab contents or a history, we will not re-issue it. Otherwise, if it
-      // may have been consumed by either tab contents or history, we will
-      // permit re-issuing another one.
-      if (!it->second->seen_history_ &&
-          !it->second->seen_tabcontents_) {
-        return false;
-      }
-    }
-    ListEntry* entry = new ListEntry(url_string);
-    entries_[entry->url_] = entry;
-    entry_list_.push_back(entry);
-    ExpireOldItems();
-    return true;
-  }
-
-  // Marks the URL provided as seen in the context specified. Returns true
-  // iff the item is currently in the list and had not been seen before in
-  // the context specified, i.e. the marking was successful.
-  bool MarkURLSeen(const GURL& url, SeenType type) {
-    ExpireOldItems();
-    bool return_value = false;
-    base::hash_map<string, ListEntry*>::iterator it =
-        entries_.find(url.spec().c_str());
-    if (it == entries_.end())
-      return return_value;
-    if (type == SEEN_TABCONTENTS_OBSERVER && !it->second->seen_tabcontents_) {
-      it->second->seen_tabcontents_ = true;
-      return_value = true;
-    }
-    if (type == SEEN_HISTORY && !it->second->seen_history_) {
-      it->second->seen_history_ = true;
-      return_value = true;
-    }
-    // If the item has been seen in both the history and in tab contents,
-    // and the page load time has been recorded, erase it from the map to
-    // make room for new prefetches.
-    if (it->second->seen_tabcontents_ && it->second->seen_history_ &&
-        it->second->seen_plt_) {
-      entries_.erase(url.spec().c_str());
-    }
-    return return_value;
-  }
-
-  // Marks the PLT for the provided UR as seen. Returns true
-  // iff the item is currently in the list and the PLT had not been seen
-  // before, i.e. the sighting was successful.
-  bool MarkPLTSeen(const GURL& url, base::TimeDelta plt) {
-    ExpireOldItems();
-    base::hash_map<string, ListEntry*>::iterator it =
-        entries_.find(url.spec().c_str());
-    if (it == entries_.end() || it->second->seen_plt_ ||
-        it->second->add_time_ > GetCurrentTime() - plt) {
-      return false;
-    }
-    it->second->seen_plt_ = true;
-    // If the item has been seen in both the history and in tab contents,
-    // and the page load time has been recorded, erase it from the map to
-    // make room for new prefetches.
-    if (it->second->seen_tabcontents_ && it->second->seen_history_ &&
-        it->second->seen_plt_) {
-      entries_.erase(url.spec().c_str());
-    }
-    return true;
-  }
-
- private:
-  struct ListEntry {
-    explicit ListEntry(const string& url)
-        : url_(url),
-          add_time_(GetCurrentTime()),
-          seen_tabcontents_(false),
-          seen_history_(false),
-          seen_plt_(false) {
-    }
-    std::string url_;
-    base::Time add_time_;
-    bool seen_tabcontents_;
-    bool seen_history_;
-    bool seen_plt_;
-  };
-
-  void ExpireOldItems() {
-    base::Time expiry_cutoff = GetCurrentTime() -
-        base::TimeDelta::FromSeconds(GetPrerenderPrefetchListTimeoutSeconds());
-    while (!entry_list_.empty() &&
-           (entry_list_.front()->add_time_ < expiry_cutoff ||
-            entries_.size() > kMaxPrefetchItems)) {
-      ListEntry* entry = entry_list_.front();
-      entry_list_.pop_front();
-      // If the entry to be deleted is still the one active in entries_,
-      // we must erase it from entries_.
-      base::hash_map<string, ListEntry*>::iterator it =
-          entries_.find(entry->url_);
-      if (it != entries_.end() && it->second == entry)
-        entries_.erase(entry->url_);
-      delete entry;
-    }
-  }
-
-  base::hash_map<string, ListEntry*> entries_;
-  std::list<ListEntry*> entry_list_;
-  DISALLOW_COPY_AND_ASSIGN(PrefetchList);
-};
-
-PrerenderLocalPredictor::PrerenderLocalPredictor(
-    PrerenderManager* prerender_manager)
-    : prerender_manager_(prerender_manager),
-      prefetch_list_(new PrefetchList()),
-      history_service_observer_(this),
-      weak_factory_(this) {
-  RecordEvent(EVENT_CONSTRUCTED);
-  if (base::MessageLoop::current()) {
-    timer_.Start(FROM_HERE,
-                 base::TimeDelta::FromMilliseconds(kInitDelayMs),
-                 this,
-                 &PrerenderLocalPredictor::Init);
-    RecordEvent(EVENT_INIT_SCHEDULED);
-  }
-
-  static const size_t kChecksumHashSize = 32;
-  base::RefCountedStaticMemory* url_whitelist_data =
-      ResourceBundle::GetSharedInstance().LoadDataResourceBytes(
-          IDR_PRERENDER_URL_WHITELIST);

[mmenke, 2015/04/10 16:42:04]

Also remove this resource (File and GRD entry)?  Looks to be empty, anyways.

[davidben, 2015/04/13 15:51:14]

Done.

-  size_t size = url_whitelist_data->size();
-  const unsigned char* front = url_whitelist_data->front();
-  if (size < kChecksumHashSize ||
-      (size - kChecksumHashSize) % kURLHashSize != 0) {
-    RecordEvent(EVENT_URL_WHITELIST_ERROR);
-    return;
-  }
-  scoped_ptr<crypto::SecureHash> hash(
-      crypto::SecureHash::Create(crypto::SecureHash::SHA256));
-  hash->Update(front + kChecksumHashSize, size - kChecksumHashSize);
-  char hash_value[kChecksumHashSize];
-  hash->Finish(hash_value, kChecksumHashSize);
-  if (memcmp(hash_value, front, kChecksumHashSize)) {
-    RecordEvent(EVENT_URL_WHITELIST_ERROR);
-    return;
-  }
-  for (const unsigned char* p = front + kChecksumHashSize;
-       p < front + size;
-       p += kURLHashSize) {
-    url_whitelist_.insert(URLHashToInt64(p));
-  }
-  RecordEvent(EVENT_URL_WHITELIST_OK);
-}
-
-PrerenderLocalPredictor::~PrerenderLocalPredictor() {
-  Shutdown();
-  for (PrerenderProperties* p : issued_prerenders_) {
-    DCHECK(p != NULL);
-    if (p->prerender_handle)
-      p->prerender_handle->OnCancel();
-  }
-  STLDeleteContainerPairPointers(
-      outstanding_prerender_service_requests_.begin(),
-      outstanding_prerender_service_requests_.end());
-}
-
-void PrerenderLocalPredictor::Shutdown() {
-  timer_.Stop();
-  history_service_observer_.RemoveAll();
-}
-
-void PrerenderLocalPredictor::OnAddVisit(
-    history::HistoryService* history_service,
-    const history::BriefVisitInfo& info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  RecordEvent(EVENT_ADD_VISIT);
-  if (!visit_history_.get())
-    return;
-  visit_history_->push_back(info);
-  if (static_cast<int>(visit_history_->size()) > kVisitHistoryPruneThreshold) {
-    visit_history_->erase(visit_history_->begin(),
-                          visit_history_->begin() + kVisitHistoryPruneAmount);
-  }
-  RecordEvent(EVENT_ADD_VISIT_INITIALIZED);
-  if (current_prerender_.get() &&
-      current_prerender_->url_id == info.url_id &&
-      IsPrerenderStillValid(current_prerender_.get())) {
-    UMA_HISTOGRAM_CUSTOM_TIMES(
-        "Prerender.LocalPredictorTimeUntilUsed",

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-        GetCurrentTime() - current_prerender_->actual_start_time,
-        base::TimeDelta::FromMilliseconds(10),
-        base::TimeDelta::FromMilliseconds(GetMaxLocalPredictionTimeMs()),
-        50);
-    last_swapped_in_prerender_.reset(current_prerender_.release());
-    RecordEvent(EVENT_ADD_VISIT_PRERENDER_IDENTIFIED);
-  }
-  if (ShouldExcludeTransitionForPrediction(info.transition))
-    return;
-  Profile* profile = prerender_manager_->profile();
-  if (!profile ||
-      ShouldDisableLocalPredictorDueToPreferencesAndNetwork(profile)) {
-    return;
-  }
-  RecordEvent(EVENT_ADD_VISIT_RELEVANT_TRANSITION);
-  base::TimeDelta max_age =
-      base::TimeDelta::FromMilliseconds(GetMaxLocalPredictionTimeMs());
-  base::TimeDelta min_age =
-      base::TimeDelta::FromMilliseconds(kMinLocalPredictionTimeMs);
-  std::set<URLID> next_urls_currently_found;
-  std::map<URLID, int> next_urls_num_found;
-  int num_occurrences_of_current_visit = 0;
-  base::Time last_visited;
-  scoped_ptr<CandidatePrerenderInfo> lookup_info(
-      new CandidatePrerenderInfo(info.url_id));
-  const vector<history::BriefVisitInfo>& visits = *(visit_history_.get());
-  for (int i = 0; i < static_cast<int>(visits.size()); i++) {
-    if (!ShouldExcludeTransitionForPrediction(visits[i].transition)) {
-      if (visits[i].url_id == info.url_id) {
-        last_visited = visits[i].time;
-        num_occurrences_of_current_visit++;
-        next_urls_currently_found.clear();
-        continue;
-      }
-      if (!last_visited.is_null() &&
-          last_visited > visits[i].time - max_age &&
-          last_visited < visits[i].time - min_age) {
-        if (!IsFormSubmit(visits[i].transition))
-          next_urls_currently_found.insert(visits[i].url_id);
-      }
-    }
-    if (i == static_cast<int>(visits.size()) - 1 ||
-        visits[i+1].url_id == info.url_id) {
-      for (std::set<URLID>::iterator it = next_urls_currently_found.begin();
-           it != next_urls_currently_found.end();
-           ++it) {
-        std::pair<std::map<URLID, int>::iterator, bool> insert_ret =
-            next_urls_num_found.insert(std::pair<URLID, int>(*it, 0));
-        std::map<URLID, int>::iterator num_found_it = insert_ret.first;
-        num_found_it->second++;
-      }
-    }
-  }
-
-  if (num_occurrences_of_current_visit > 1) {
-    RecordEvent(EVENT_ADD_VISIT_RELEVANT_TRANSITION_REPEAT_URL);
-  } else {
-    RecordEvent(EVENT_ADD_VISIT_RELEVANT_TRANSITION_NEW_URL);
-  }
-
-  for (std::map<URLID, int>::const_iterator it = next_urls_num_found.begin();
-       it != next_urls_num_found.end();
-       ++it) {
-    // Only consider a candidate next page for prerendering if it was viewed
-    // at least twice, and at least 10% of the time.
-    if (num_occurrences_of_current_visit > 0 &&
-        it->second > 1 &&
-        it->second * 10 >= num_occurrences_of_current_visit) {
-      RecordEvent(EVENT_ADD_VISIT_IDENTIFIED_PRERENDER_CANDIDATE);
-      double priority = static_cast<double>(it->second) /
-          static_cast<double>(num_occurrences_of_current_visit);
-      lookup_info->MaybeAddCandidateURLFromLocalData(it->first, priority);
-    }
-  }
-
-  RecordEvent(EVENT_START_URL_LOOKUP);
-  history::HistoryService* history = GetHistoryIfExists();
-  if (history) {
-    RecordEvent(EVENT_GOT_HISTORY_ISSUING_LOOKUP);
-    CandidatePrerenderInfo* lookup_info_ptr = lookup_info.get();
-    history->ScheduleDBTask(
-        scoped_ptr<history::HistoryDBTask>(
-            new GetURLForURLIDTask(
-                lookup_info_ptr,
-                base::Bind(&PrerenderLocalPredictor::OnLookupURL,
-                           base::Unretained(this),
-                           base::Passed(&lookup_info)))),
-        &history_db_tracker_);
-  }
-}
-
-void PrerenderLocalPredictor::OnLookupURL(
-    scoped_ptr<CandidatePrerenderInfo> info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT);
-
-  if (!info->source_url_.url_lookup_success) {
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_FAILED);
-    return;
-  }
-
-  if (prefetch_list_->MarkURLSeen(info->source_url_.url,
-                                  PrefetchList::SEEN_HISTORY)) {
-    RecordEvent(EVENT_PREFETCH_LIST_SEEN_HISTORY);
-  }
-
-  if (info->candidate_urls_.size() > 0 &&
-      info->candidate_urls_[0].url_lookup_success) {
-    LogCandidateURLStats(info->candidate_urls_[0].url);
-  }
-
-  WebContents* source_web_contents = NULL;
-  bool multiple_source_web_contents_candidates = false;
-
-#if !defined(OS_ANDROID)
-  // We need to figure out what tab launched the prerender. We do this by
-  // comparing URLs. This may not always work: the URL may occur in two
-  // tabs, and we pick the wrong one, or the tab we should have picked
-  // may have navigated elsewhere. Hopefully, this doesn't happen too often,
-  // so we ignore these cases for now.
-  // TODO(tburkard): Reconsider this, potentially measure it, and fix this
-  // in the future.
-  for (TabContentsIterator it; !it.done(); it.Next()) {
-    if (it->GetURL() == info->source_url_.url) {
-      if (!source_web_contents)
-        source_web_contents = *it;
-      else
-        multiple_source_web_contents_candidates = true;
-    }
-  }
-#endif
-
-  if (!source_web_contents) {
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_NO_SOURCE_WEBCONTENTS_FOUND);
-    return;
-  }
-
-  if (multiple_source_web_contents_candidates)
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_MULTIPLE_SOURCE_WEBCONTENTS_FOUND);
-
-  info->session_storage_namespace_ =
-      source_web_contents->GetController().GetDefaultSessionStorageNamespace();
-  RenderFrameHost* rfh = source_web_contents->GetMainFrame();
-  info->render_process_id_ = rfh->GetProcess()->GetID();
-  info->render_frame_id_ = rfh->GetRoutingID();
-
-  gfx::Rect container_bounds = source_web_contents->GetContainerBounds();
-  info->size_.reset(new gfx::Size(container_bounds.size()));
-
-  RecordEvent(EVENT_PRERENDER_URL_LOOKUP_SUCCESS);
-
-  DoPrerenderServiceCheck(info.Pass());
-}
-
-void PrerenderLocalPredictor::DoPrerenderServiceCheck(
-    scoped_ptr<CandidatePrerenderInfo> info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (!ShouldQueryPrerenderService(prerender_manager_->profile())) {
-    RecordEvent(EVENT_PRERENDER_SERVICE_DISABLED);
-    DoLoggedInLookup(info.Pass());
-    return;
-  }
-  /*
-    Create a JSON request.
-    Here is a sample request:
-    { "prerender_request": {
-        "version": 1,
-        "behavior_id": 6,
-        "hint_request": {
-          "browse_history": [
-            { "url": "http://www.cnn.com/"
-            }
-          ]
-        },
-        "candidate_check_request": {
-          "candidates": [
-            { "url": "http://www.cnn.com/sports/"
-            },
-            { "url": "http://www.cnn.com/politics/"
-            }
-          ]
-        }
-      }
-    }
-  */
-  base::DictionaryValue json_data;
-  base::DictionaryValue* req = new base::DictionaryValue();
-  req->SetInteger("version", 1);
-  req->SetInteger("behavior_id", GetPrerenderServiceBehaviorID());
-  if (ShouldQueryPrerenderServiceForCurrentURL() &&
-      info->source_url_.url_lookup_success) {
-    base::ListValue* browse_history = new base::ListValue();
-    base::DictionaryValue* browse_item = new base::DictionaryValue();
-    browse_item->SetString("url", info->source_url_.url.spec());
-    browse_history->Append(browse_item);
-    base::DictionaryValue* hint_request = new base::DictionaryValue();
-    hint_request->Set("browse_history", browse_history);
-    req->Set("hint_request", hint_request);
-  }
-  int num_candidate_urls = 0;
-  for (int i = 0; i < static_cast<int>(info->candidate_urls_.size()); i++) {
-    if (info->candidate_urls_[i].url_lookup_success)
-      num_candidate_urls++;
-  }
-  if (ShouldQueryPrerenderServiceForCandidateURLs() &&
-      num_candidate_urls > 0) {
-    base::ListValue* candidates = new base::ListValue();
-    base::DictionaryValue* candidate;
-    for (int i = 0; i < static_cast<int>(info->candidate_urls_.size()); i++) {
-      if (info->candidate_urls_[i].url_lookup_success) {
-        candidate = new base::DictionaryValue();
-        candidate->SetString("url", info->candidate_urls_[i].url.spec());
-        candidates->Append(candidate);
-      }
-    }
-    base::DictionaryValue* candidate_check_request =
-        new base::DictionaryValue();
-    candidate_check_request->Set("candidates", candidates);
-    req->Set("candidate_check_request", candidate_check_request);
-  }
-  json_data.Set("prerender_request", req);
-  string request_string;
-  base::JSONWriter::Write(&json_data, &request_string);
-  GURL fetch_url(GetPrerenderServiceURLPrefix() +
-                 net::EscapeQueryParamValue(request_string, false));
-  net::URLFetcher* fetcher = net::URLFetcher::Create(
-      0,
-      fetch_url,
-      URLFetcher::GET, this);
-  fetcher->SetRequestContext(
-      prerender_manager_->profile()->GetRequestContext());
-  fetcher->SetLoadFlags(net::LOAD_DISABLE_CACHE |
-                        net::LOAD_DO_NOT_SAVE_COOKIES |
-                        net::LOAD_DO_NOT_SEND_COOKIES);
-  fetcher->AddExtraRequestHeader("Pragma: no-cache");
-  info->start_time_ = base::Time::Now();
-  outstanding_prerender_service_requests_.insert(
-      std::make_pair(fetcher, info.release()));
-  base::MessageLoop::current()->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(&PrerenderLocalPredictor::MaybeCancelURLFetcher,
-                 weak_factory_.GetWeakPtr(), fetcher),
-      base::TimeDelta::FromMilliseconds(GetPrerenderServiceFetchTimeoutMs()));
-  RecordEvent(EVENT_PRERENDER_SERVICE_ISSUED_LOOKUP);
-  fetcher->Start();
-}
-
-void PrerenderLocalPredictor::MaybeCancelURLFetcher(net::URLFetcher* fetcher) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  OutstandingFetchers::iterator it =
-      outstanding_prerender_service_requests_.find(fetcher);
-  if (it == outstanding_prerender_service_requests_.end())
-    return;
-  delete it->first;
-  scoped_ptr<CandidatePrerenderInfo> info(it->second);
-  outstanding_prerender_service_requests_.erase(it);
-  RecordEvent(EVENT_PRERENDER_SERVICE_LOOKUP_TIMED_OUT);
-  DoLoggedInLookup(info.Pass());
-}
-
-bool PrerenderLocalPredictor::ApplyParsedPrerenderServiceResponse(
-    base::DictionaryValue* dict,
-    CandidatePrerenderInfo* info,
-    bool* hinting_timed_out,
-    bool* hinting_url_lookup_timed_out,
-    bool* candidate_url_lookup_timed_out) {
-  /*
-    Process the response to the request.
-    Here is a sample response to illustrate the format.
-    {
-      "prerender_response": {
-        "behavior_id": 6,
-        "hint_response": {
-          "hinting_timed_out": 0,
-          "candidates": [
-            { "url": "http://www.cnn.com/story-1",
-              "in_index": 1,
-              "likelihood": 0.60,
-              "in_index_timed_out": 0
-            },
-            { "url": "http://www.cnn.com/story-2",
-              "in_index": 1,
-              "likelihood": 0.30,
-              "in_index_timed_out": 0
-            }
-          ]
-        },
-        "candidate_check_response": {
-          "candidates": [
-            { "url": "http://www.cnn.com/sports/",
-              "in_index": 1,
-              "in_index_timed_out": 0
-            },
-            { "url": "http://www.cnn.com/politics/",
-              "in_index": 0,
-              "in_index_timed_out": "1"
-            }
-          ]
-        }
-      }
-    }
-  */
-  base::ListValue* list = NULL;
-  int int_value;
-  if (!dict->GetInteger("prerender_response.behavior_id", &int_value) ||
-      int_value != GetPrerenderServiceBehaviorID()) {
-    return false;
-  }
-  if (!dict->GetList("prerender_response.candidate_check_response.candidates",
-                     &list)) {
-    if (ShouldQueryPrerenderServiceForCandidateURLs()) {
-      for (int i = 0; i < static_cast<int>(info->candidate_urls_.size()); i++) {
-        if (info->candidate_urls_[i].url_lookup_success)
-          return false;
-      }
-    }
-  } else {
-    for (size_t i = 0; i < list->GetSize(); i++) {
-      base::DictionaryValue* d;
-      if (!list->GetDictionary(i, &d))
-        return false;
-      string url_string;
-      if (!d->GetString("url", &url_string) || !GURL(url_string).is_valid())
-        return false;
-      GURL url(url_string);
-      int in_index_timed_out = 0;
-      int in_index = 0;
-      if ((!d->GetInteger("in_index_timed_out", &in_index_timed_out) ||
-           in_index_timed_out != 1) &&
-          !d->GetInteger("in_index", &in_index)) {
-        return false;
-      }
-      if (in_index < 0 || in_index > 1 ||
-          in_index_timed_out < 0 || in_index_timed_out > 1) {
-        return false;
-      }
-      if (in_index_timed_out == 1)
-        *candidate_url_lookup_timed_out = true;
-      for (size_t j = 0; j < info->candidate_urls_.size(); j++) {
-        if (info->candidate_urls_[j].url == url) {
-          info->candidate_urls_[j].service_whitelist_reported = true;
-          info->candidate_urls_[j].service_whitelist = (in_index == 1);
-          info->candidate_urls_[j].service_whitelist_lookup_ok =
-              ((1 - in_index_timed_out) == 1);
-        }
-      }
-    }
-    for (size_t i = 0; i < info->candidate_urls_.size(); i++) {
-      if (info->candidate_urls_[i].url_lookup_success &&
-          !info->candidate_urls_[i].service_whitelist_reported) {
-        return false;
-      }
-    }
-  }
-
-  if (ShouldQueryPrerenderServiceForCurrentURL() &&
-      info->source_url_.url_lookup_success) {
-    list = NULL;
-    if (dict->GetInteger("prerender_response.hint_response.hinting_timed_out",
-                         &int_value) &&
-        int_value == 1) {
-      *hinting_timed_out = true;
-    } else if (!dict->GetList("prerender_response.hint_response.candidates",
-                              &list)) {
-      return false;
-    } else {
-      for (int i = 0; i < static_cast<int>(list->GetSize()); i++) {
-        base::DictionaryValue* d;
-        if (!list->GetDictionary(i, &d))
-          return false;
-        string url;
-        if (!d->GetString("url", &url) || !GURL(url).is_valid())
-          return false;
-        double priority;
-        if (!d->GetDouble("likelihood", &priority) || priority < 0.0 ||
-            priority > 1.0) {
-          return false;
-        }
-        int in_index_timed_out = 0;
-        int in_index = 0;
-        if ((!d->GetInteger("in_index_timed_out", &in_index_timed_out) ||
-             in_index_timed_out != 1) &&
-            !d->GetInteger("in_index", &in_index)) {
-          return false;
-        }
-        if (in_index < 0 || in_index > 1 || in_index_timed_out < 0 ||
-            in_index_timed_out > 1) {
-          return false;
-        }
-        if (in_index_timed_out == 1)
-          *hinting_url_lookup_timed_out = true;
-        info->MaybeAddCandidateURLFromService(GURL(url),
-                                              priority,
-                                              in_index == 1,
-                                              !in_index_timed_out);
-      }
-      if (list->GetSize() > 0)
-        RecordEvent(EVENT_PRERENDER_SERVICE_RETURNED_HINTING_CANDIDATES);
-    }
-  }
-
-  return true;
-}
-
-void PrerenderLocalPredictor::OnURLFetchComplete(
-    const net::URLFetcher* source) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  RecordEvent(EVENT_PRERENDER_SERVICE_RECEIVED_RESULT);
-  net::URLFetcher* fetcher = const_cast<net::URLFetcher*>(source);
-  OutstandingFetchers::iterator it =
-      outstanding_prerender_service_requests_.find(fetcher);
-  if (it == outstanding_prerender_service_requests_.end()) {
-    RecordEvent(EVENT_PRERENDER_SERVICE_NO_RECORD_FOR_RESULT);
-    return;
-  }
-  scoped_ptr<CandidatePrerenderInfo> info(it->second);
-  outstanding_prerender_service_requests_.erase(it);
-  TIMING_HISTOGRAM("Prerender.LocalPredictorServiceLookupTime",
-                   base::Time::Now() - info->start_time_);

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-  string result;
-  fetcher->GetResponseAsString(&result);
-  scoped_ptr<base::Value> root;
-  root.reset(base::JSONReader::Read(result));
-  bool hinting_timed_out = false;
-  bool hinting_url_lookup_timed_out = false;
-  bool candidate_url_lookup_timed_out = false;
-  if (!root.get() || !root->IsType(base::Value::TYPE_DICTIONARY)) {
-    RecordEvent(EVENT_PRERENDER_SERVICE_PARSE_ERROR_INCORRECT_JSON);
-  } else {
-    if (ApplyParsedPrerenderServiceResponse(
-            static_cast<base::DictionaryValue*>(root.get()),
-            info.get(),
-            &hinting_timed_out,
-            &hinting_url_lookup_timed_out,
-            &candidate_url_lookup_timed_out)) {
-      // We finished parsing the result, and found no errors.
-      RecordEvent(EVENT_PRERENDER_SERVICE_PARSED_CORRECTLY);
-      if (hinting_timed_out)
-        RecordEvent(EVENT_PRERENDER_SERVICE_HINTING_TIMED_OUT);
-      if (hinting_url_lookup_timed_out)
-        RecordEvent(EVENT_PRERENDER_SERVICE_HINTING_URL_LOOKUP_TIMED_OUT);
-      if (candidate_url_lookup_timed_out)
-        RecordEvent(EVENT_PRERENDER_SERVICE_CANDIDATE_URL_LOOKUP_TIMED_OUT);
-      DoLoggedInLookup(info.Pass());
-      return;
-    }
-  }
-
-  // If we did not return earlier, an error happened during parsing.
-  // Record this, and proceed.
-  RecordEvent(EVENT_PRERENDER_SERVICE_PARSE_ERROR);
-  DoLoggedInLookup(info.Pass());
-}
-
-void PrerenderLocalPredictor:: DoLoggedInLookup(
-    scoped_ptr<CandidatePrerenderInfo> info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  scoped_refptr<LoggedInPredictorTable> logged_in_table =
-      prerender_manager_->logged_in_predictor_table();
-
-  if (!logged_in_table.get()) {
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_NO_LOGGED_IN_TABLE_FOUND);
-    return;
-  }
-
-  RecordEvent(EVENT_PRERENDER_URL_LOOKUP_ISSUING_LOGGED_IN_LOOKUP);
-
-  info->start_time_ = base::Time::Now();
-
-  CandidatePrerenderInfo* info_ptr = info.get();
-  BrowserThread::PostTaskAndReply(
-      BrowserThread::DB, FROM_HERE,
-      base::Bind(&LookupLoggedInStatesOnDBThread,
-                 logged_in_table,
-                 info_ptr),
-      base::Bind(&PrerenderLocalPredictor::ContinuePrerenderCheck,
-                 weak_factory_.GetWeakPtr(),
-                 base::Passed(&info)));
-}
-
-void PrerenderLocalPredictor::LogCandidateURLStats(const GURL& url) const {
-  if (url_whitelist_.count(GetInt64URLHashForURL(url)) > 0) {
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST);
-    if (IsRootPageURL(url))
-      RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_ON_WHITELIST_ROOT_PAGE);
-  }
-  if (IsRootPageURL(url))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE);
-  if (IsExtendedRootURL(url))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_EXTENDED_ROOT_PAGE);
-  if (IsRootPageURL(url) && url.SchemeIs("http"))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_ROOT_PAGE_HTTP);
-  if (url.SchemeIs("http"))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_IS_HTTP);
-  if (url.has_query())
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_HAS_QUERY_STRING);
-  if (IsLogOutURL(url))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGOUT);
-  if (IsLogInURL(url))
-    RecordEvent(EVENT_PRERENDER_URL_LOOKUP_RESULT_CONTAINS_LOGIN);
-}
-
-void PrerenderLocalPredictor::OnGetInitialVisitHistory(
-    scoped_ptr<vector<history::BriefVisitInfo> > visit_history) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(!visit_history_.get());
-  RecordEvent(EVENT_INIT_SUCCEEDED);
-  // Since the visit history has descending timestamps, we must reverse it.
-  visit_history_.reset(new vector<history::BriefVisitInfo>(
-      visit_history->rbegin(), visit_history->rend()));
-}
-
-history::HistoryService* PrerenderLocalPredictor::GetHistoryIfExists() const {
-  Profile* profile = prerender_manager_->profile();
-  if (!profile)
-    return NULL;
-  return HistoryServiceFactory::GetForProfileWithoutCreating(profile);
-}
-
-void PrerenderLocalPredictor::Init() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  RecordEvent(EVENT_INIT_STARTED);
-  Profile* profile = prerender_manager_->profile();
-  if (!profile ||
-      ShouldDisableLocalPredictorBasedOnSyncAndConfiguration(profile)) {
-    RecordEvent(EVENT_INIT_FAILED_UNENCRYPTED_SYNC_NOT_ENABLED);
-    return;
-  }
-  history::HistoryService* history = GetHistoryIfExists();
-  if (history) {
-    CHECK(!history_service_observer_.IsObserving(history));
-    history->ScheduleDBTask(
-        scoped_ptr<history::HistoryDBTask>(
-            new GetVisitHistoryTask(this, kMaxVisitHistory)),
-        &history_db_tracker_);
-    history_service_observer_.Add(history);
-  } else {
-    RecordEvent(EVENT_INIT_FAILED_NO_HISTORY);
-  }
-}
-
-void PrerenderLocalPredictor::OnPLTEventForURL(const GURL& url,
-                                               base::TimeDelta page_load_time) {
-  if (prefetch_list_->MarkPLTSeen(url, page_load_time)) {
-    UMA_HISTOGRAM_CUSTOM_TIMES("Prerender.LocalPredictorPrefetchMatchPLT",
-                               page_load_time,
-                               base::TimeDelta::FromMilliseconds(10),
-                               base::TimeDelta::FromSeconds(60),
-                               100);

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-  }
-
-  scoped_ptr<PrerenderProperties> prerender;
-  if (DoesPrerenderMatchPLTRecord(last_swapped_in_prerender_.get(),
-                                  url, page_load_time)) {
-    prerender.reset(last_swapped_in_prerender_.release());
-  }
-  if (DoesPrerenderMatchPLTRecord(current_prerender_.get(),
-                                  url, page_load_time)) {
-    prerender.reset(current_prerender_.release());
-  }
-  if (!prerender.get())
-    return;
-  if (IsPrerenderStillValid(prerender.get())) {
-    UMA_HISTOGRAM_CUSTOM_TIMES("Prerender.SimulatedLocalBrowsingBaselinePLT",

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-                               page_load_time,
-                               base::TimeDelta::FromMilliseconds(10),
-                               base::TimeDelta::FromSeconds(60),
-                               100);
-
-    base::TimeDelta prerender_age = GetCurrentTime() - prerender->start_time;
-    if (prerender_age > page_load_time) {
-      base::TimeDelta new_plt;
-      if (prerender_age <  2 * page_load_time)
-        new_plt = 2 * page_load_time - prerender_age;
-      UMA_HISTOGRAM_CUSTOM_TIMES("Prerender.SimulatedLocalBrowsingPLT",

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-                                 new_plt,
-                                 base::TimeDelta::FromMilliseconds(10),
-                                 base::TimeDelta::FromSeconds(60),
-                                 100);
-    }
-  }
-}
-
-bool PrerenderLocalPredictor::IsPrerenderStillValid(
-    PrerenderLocalPredictor::PrerenderProperties* prerender) const {
-  return (prerender &&
-          (prerender->start_time +
-           base::TimeDelta::FromMilliseconds(GetMaxLocalPredictionTimeMs()))
-          > GetCurrentTime());
-}
-
-void PrerenderLocalPredictor::RecordEvent(
-    PrerenderLocalPredictor::Event event) const {
-  UMA_HISTOGRAM_ENUMERATION("Prerender.LocalPredictorEvent",

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-      event, PrerenderLocalPredictor::EVENT_MAX_VALUE);
-}
-
-bool PrerenderLocalPredictor::DoesPrerenderMatchPLTRecord(
-    PrerenderProperties* prerender,
-    const GURL& url,
-    base::TimeDelta plt) const {
-  if (prerender && prerender->start_time < GetCurrentTime() - plt) {
-    if (prerender->url.is_empty())
-      RecordEvent(EVENT_ERROR_NO_PRERENDER_URL_FOR_PLT);
-    return (prerender->url == url);
-  } else {
-    return false;
-  }
-}
-
-PrerenderLocalPredictor::PrerenderProperties*
-PrerenderLocalPredictor::GetIssuedPrerenderSlotForPriority(const GURL& url,
-                                                           double priority) {
-  int num_prerenders = GetLocalPredictorMaxConcurrentPrerenders();
-  while (static_cast<int>(issued_prerenders_.size()) < num_prerenders)
-    issued_prerenders_.push_back(new PrerenderProperties());
-  // First, check if we already have a prerender for the same URL issued.
-  // If yes, we don't want to prerender this URL again, so we return NULL
-  // (on matching slot found).
-  for (int i = 0; i < static_cast<int>(issued_prerenders_.size()); i++) {
-    PrerenderProperties* p = issued_prerenders_[i];
-    DCHECK(p != NULL);
-    if (p->prerender_handle && p->prerender_handle->IsPrerendering() &&
-        p->prerender_handle->Matches(url, NULL)) {
-      return NULL;
-    }
-  }
-  // Otherwise, let's see if there are any empty slots. If yes, return the first
-  // one we find. Otherwise, if the lowest priority prerender has a lower
-  // priority than the page we want to prerender, use its slot.
-  PrerenderProperties* lowest_priority_prerender = NULL;
-  for (int i = 0; i < static_cast<int>(issued_prerenders_.size()); i++) {
-    PrerenderProperties* p = issued_prerenders_[i];
-    DCHECK(p != NULL);
-    if (!p->prerender_handle || !p->prerender_handle->IsPrerendering())
-      return p;
-    double decayed_priority = p->GetCurrentDecayedPriority();
-    if (decayed_priority > priority)
-      continue;
-    if (lowest_priority_prerender == NULL ||
-        lowest_priority_prerender->GetCurrentDecayedPriority() >
-        decayed_priority) {
-      lowest_priority_prerender = p;
-    }
-  }
-  return lowest_priority_prerender;
-}
-
-void PrerenderLocalPredictor::ContinuePrerenderCheck(
-    scoped_ptr<CandidatePrerenderInfo> info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  TIMING_HISTOGRAM("Prerender.LocalPredictorLoggedInLookupTime",
-                   base::Time::Now() - info->start_time_);

[mmenke, 2015/04/10 16:42:04]

Obsolete UMA

[davidben, 2015/04/13 15:51:14]

Done.

-  RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_STARTED);
-  if (info->candidate_urls_.size() == 0) {
-    RecordEvent(EVENT_NO_PRERENDER_CANDIDATES);
-    return;
-  }
-  scoped_ptr<LocalPredictorURLInfo> url_info;
-#if defined(FULL_SAFE_BROWSING)
-  scoped_refptr<SafeBrowsingDatabaseManager> sb_db_manager =
-      g_browser_process->safe_browsing_service()->database_manager();
-#endif
-  int num_issued = 0;
-  for (int i = 0; i < static_cast<int>(info->candidate_urls_.size()); i++) {
-    if (num_issued >= GetLocalPredictorMaxLaunchPrerenders())
-      return;
-    RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL);
-    url_info.reset(new LocalPredictorURLInfo(info->candidate_urls_[i]));
-    if (url_info->local_history_based) {
-      if (SkipLocalPredictorLocalCandidates()) {
-        url_info.reset(NULL);
-        continue;
-      }
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_LOCAL);
-    }
-    if (!url_info->local_history_based) {
-      if (SkipLocalPredictorServiceCandidates()) {
-        url_info.reset(NULL);
-        continue;
-      }
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_SERVICE);
-    }
-
-    RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_EXAMINE_NEXT_URL_NOT_SKIPPED);
-
-    // We need to check whether we can issue a prerender for this URL.
-    // We test a set of conditions. Each condition can either rule out
-    // a prerender (in which case we reset url_info, so that it will not
-    // be prerendered, and we continue, which means try the next candidate
-    // URL), or it can be sufficient to issue the prerender without any
-    // further checks (in which case we just break).
-    // The order of the checks is critical, because it prescribes the logic
-    // we use here to decide what to prerender.
-    if (!url_info->url_lookup_success) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_NO_URL);
-      url_info.reset(NULL);
-      continue;
-    }
-    if (!SkipLocalPredictorFragment() &&
-        URLsIdenticalIgnoringFragments(info->source_url_.url,
-                                       url_info->url)) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_URLS_IDENTICAL_BUT_FRAGMENT);
-      url_info.reset(NULL);
-      continue;
-    }
-    if (!SkipLocalPredictorHTTPS() && url_info->url.SchemeIs("https")) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_HTTPS);
-      url_info.reset(NULL);
-      continue;
-    }
-    if (IsRootPageURL(url_info->url)) {
-      // For root pages, we assume that they are reasonably safe, and we
-      // will just prerender them without any additional checks.
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_ROOT_PAGE);
-      IssuePrerender(info.get(), url_info.get());
-      num_issued++;
-      continue;
-    }
-    if (IsLogOutURL(url_info->url)) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_LOGOUT_URL);
-      url_info.reset(NULL);
-      continue;
-    }
-    if (IsLogInURL(url_info->url)) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_LOGIN_URL);
-      url_info.reset(NULL);
-      continue;
-    }
-#if defined(FULL_SAFE_BROWSING)
-    if (!SkipLocalPredictorWhitelist() && sb_db_manager.get() &&
-        sb_db_manager->CheckSideEffectFreeWhitelistUrl(url_info->url)) {
-      // If a page is on the side-effect free whitelist, we will just prerender
-      // it without any additional checks.
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_ON_SIDE_EFFECT_FREE_WHITELIST);
-      IssuePrerender(info.get(), url_info.get());
-      num_issued++;
-      continue;
-    }
-#endif
-    if (!SkipLocalPredictorServiceWhitelist() &&
-        url_info->service_whitelist && url_info->service_whitelist_lookup_ok) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_ON_SERVICE_WHITELIST);
-      IssuePrerender(info.get(), url_info.get());
-      num_issued++;
-      continue;
-    }
-    if (!SkipLocalPredictorLoggedIn() &&
-        !url_info->logged_in && url_info->logged_in_lookup_ok) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_NOT_LOGGED_IN);
-      IssuePrerender(info.get(), url_info.get());
-      num_issued++;
-      continue;
-    }
-    if (!SkipLocalPredictorDefaultNoPrerender()) {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_NOT_PRERENDERING);
-      url_info.reset(NULL);
-    } else {
-      RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_PRERENDERING);
-      IssuePrerender(info.get(), url_info.get());
-      num_issued++;
-      continue;
-    }
-  }
-}
-
-void PrerenderLocalPredictor::IssuePrerender(
-    CandidatePrerenderInfo* info,
-    LocalPredictorURLInfo* url_info) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  RecordEvent(EVENT_ISSUE_PRERENDER_CALLED);
-  if (prefetch_list_->AddURL(url_info->url)) {
-    RecordEvent(EVENT_PREFETCH_LIST_ADDED);
-    // If we are prefetching rather than prerendering, now is the time to launch
-    // the prefetch.
-    if (IsLocalPredictorPrerenderPrefetchEnabled()) {
-      RecordEvent(EVENT_ISSUE_PRERENDER_PREFETCH_ENABLED);
-      // Obtain the render frame host that caused this prefetch.
-      RenderFrameHost* rfh = RenderFrameHost::FromID(info->render_process_id_,
-                                                     info->render_frame_id_);
-      // If it is still alive, launch the prefresh.
-      if (rfh) {
-        rfh->Send(new PrefetchMsg_Prefetch(rfh->GetRoutingID(), url_info->url));
-        RecordEvent(EVENT_ISSUE_PRERENDER_PREFETCH_ISSUED);
-      }
-    }
-  }
-  PrerenderProperties* prerender_properties =
-      GetIssuedPrerenderSlotForPriority(url_info->url, url_info->priority);
-  if (!prerender_properties) {
-    RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_PRIORITY_TOO_LOW);
-    return;
-  }
-  RecordEvent(EVENT_CONTINUE_PRERENDER_CHECK_ISSUING_PRERENDER);
-  DCHECK(prerender_properties != NULL);
-  DCHECK(info != NULL);
-  DCHECK(url_info != NULL);
-  if (!IsLocalPredictorPrerenderLaunchEnabled())
-    return;
-  URLID url_id = url_info->id;
-  const GURL& url = url_info->url;
-  double priority = url_info->priority;
-  base::Time current_time = GetCurrentTime();
-  RecordEvent(EVENT_ISSUING_PRERENDER);
-
-  // Issue the prerender and obtain a new handle.
-  scoped_ptr<prerender::PrerenderHandle> new_prerender_handle(
-      prerender_manager_->AddPrerenderFromLocalPredictor(
-          url, info->session_storage_namespace_.get(), *(info->size_)));
-
-  // Check if this is a duplicate of an existing prerender. If yes, clean up
-  // the new handle.
-  for (int i = 0; i < static_cast<int>(issued_prerenders_.size()); i++) {
-    PrerenderProperties* p = issued_prerenders_[i];
-    DCHECK(p != NULL);
-    if (new_prerender_handle &&
-        new_prerender_handle->RepresentingSamePrerenderAs(
-            p->prerender_handle.get())) {
-      new_prerender_handle->OnCancel();
-      new_prerender_handle.reset(NULL);
-      RecordEvent(EVENT_ISSUE_PRERENDER_ALREADY_PRERENDERING);
-      break;
-    }
-  }
-
-  if (new_prerender_handle.get()) {
-    RecordEvent(EVENT_ISSUE_PRERENDER_NEW_PRERENDER);
-    // The new prerender does not match any existing prerenders. Update
-    // prerender_properties so that it reflects the new entry.
-    prerender_properties->url_id = url_id;
-    prerender_properties->url = url;
-    prerender_properties->priority = priority;
-    prerender_properties->start_time = current_time;
-    prerender_properties->actual_start_time = current_time;
-    prerender_properties->would_have_matched = false;
-    prerender_properties->prerender_handle.swap(new_prerender_handle);
-    // new_prerender_handle now represents the old previou prerender that we
-    // are replacing. So we need to cancel it.
-    if (new_prerender_handle) {
-      new_prerender_handle->OnCancel();
-      RecordEvent(EVENT_ISSUE_PRERENDER_CANCELLED_OLD_PRERENDER);
-    }
-  }
-
-  RecordEvent(EVENT_ADD_VISIT_PRERENDERING);
-  if (current_prerender_.get() && current_prerender_->url_id == url_id) {
-    RecordEvent(EVENT_ADD_VISIT_PRERENDERING_EXTENDED);
-    if (priority > current_prerender_->priority)
-      current_prerender_->priority = priority;
-    // If the prerender already existed, we want to extend it.  However,
-    // we do not want to set its start_time to the current time to
-    // disadvantage PLT computations when the prerender is swapped in.
-    // So we set the new start time to current_time - 10s (since the vast
-    // majority of PLTs are < 10s), provided that is not before the actual
-    // time the prerender was started (so as to not artificially advantage
-    // the PLT computation).
-    base::Time simulated_new_start_time =
-        current_time - base::TimeDelta::FromSeconds(10);
-    if (simulated_new_start_time > current_prerender_->start_time)
-      current_prerender_->start_time = simulated_new_start_time;
-  } else {
-    current_prerender_.reset(
-        new PrerenderProperties(url_id, url, priority, current_time));
-  }
-  current_prerender_->actual_start_time = current_time;
-}
-
-void PrerenderLocalPredictor::OnTabHelperURLSeen(
-    const GURL& url, WebContents* web_contents) {
-  RecordEvent(EVENT_TAB_HELPER_URL_SEEN);
-
-  if (prefetch_list_->MarkURLSeen(url, PrefetchList::SEEN_TABCONTENTS_OBSERVER))
-    RecordEvent(EVENT_PREFETCH_LIST_SEEN_TABCONTENTS);
-  bool browser_navigate_initiated = false;
-  const content::NavigationEntry* entry =
-      web_contents->GetController().GetPendingEntry();
-  if (entry) {
-    base::string16 result;
-    browser_navigate_initiated =
-        entry->GetExtraData(kChromeNavigateExtraDataKey, &result);
-  }
-
-  // If the namespace matches and the URL matches, we might be able to swap
-  // in. However, the actual code initating the swapin is in the renderer
-  // and is checking for other criteria (such as POSTs). There may
-  // also be conditions when a swapin should happen but does not. By recording
-  // the two previous events, we can keep an eye on the magnitude of the
-  // discrepancy.
-
-  PrerenderProperties* best_matched_prerender = NULL;
-  bool session_storage_namespace_matches = false;
-  SessionStorageNamespace* tab_session_storage_namespace =
-      web_contents->GetController().GetDefaultSessionStorageNamespace();
-  for (int i = 0; i < static_cast<int>(issued_prerenders_.size()); i++) {
-    PrerenderProperties* p = issued_prerenders_[i];
-    DCHECK(p != NULL);
-    if (!p->prerender_handle.get() ||
-        !p->prerender_handle->Matches(url, NULL) ||
-        p->would_have_matched) {
-      continue;
-    }
-    if (!best_matched_prerender || !session_storage_namespace_matches) {
-      best_matched_prerender = p;
-      session_storage_namespace_matches =
-          p->prerender_handle->Matches(url, tab_session_storage_namespace);
-    }
-  }
-  if (best_matched_prerender) {
-    RecordEvent(EVENT_TAB_HELPER_URL_SEEN_MATCH);
-    if (entry)
-      RecordEvent(EVENT_TAB_HELPER_URL_SEEN_MATCH_ENTRY);
-    if (browser_navigate_initiated)
-      RecordEvent(EVENT_TAB_HELPER_URL_SEEN_MATCH_BROWSER_NAVIGATE);
-    best_matched_prerender->would_have_matched = true;
-    if (session_storage_namespace_matches) {
-      RecordEvent(EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH);
-      if (entry)
-        RecordEvent(EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_ENTRY);
-      if (browser_navigate_initiated)
-        RecordEvent(EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH_BROWSER_NAVIGATE);
-    }
-  }
-}
-
-}  // namespace prerender