Revert of Revert of Componentize HistoryURLProvider/ScoredHistoryMatch.

components/omnibox/history_url_provider.cc

+// 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 "components/omnibox/history_url_provider.h"
+
+#include <algorithm>
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"
+#include "base/prefs/pref_service.h"
+#include "base/single_thread_task_runner.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
+#include "components/bookmarks/browser/bookmark_utils.h"
+#include "components/history/core/browser/history_backend.h"
+#include "components/history/core/browser/history_database.h"
+#include "components/history/core/browser/history_service.h"
+#include "components/history/core/browser/history_types.h"
+#include "components/metrics/proto/omnibox_input_type.pb.h"
+#include "components/omnibox/autocomplete_match.h"
+#include "components/omnibox/autocomplete_provider_listener.h"
+#include "components/omnibox/autocomplete_result.h"
+#include "components/omnibox/in_memory_url_index_types.h"
+#include "components/omnibox/omnibox_field_trial.h"
+#include "components/omnibox/scored_history_match.h"
+#include "components/omnibox/url_prefix.h"
+#include "components/search_engines/search_terms_data.h"
+#include "components/search_engines/template_url_service.h"
+#include "components/url_fixer/url_fixer.h"
+#include "net/base/net_util.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+#include "url/gurl.h"
+#include "url/third_party/mozilla/url_parse.h"
+#include "url/url_util.h"
+
+namespace {
+
+// Acts like the > operator for URLInfo classes.
+bool CompareHistoryMatch(const history::HistoryMatch& a,
+                         const history::HistoryMatch& b) {
+  // A URL that has been typed at all is better than one that has never been
+  // typed.  (Note "!"s on each side)
+  if (!a.url_info.typed_count() != !b.url_info.typed_count())
+    return a.url_info.typed_count() > b.url_info.typed_count();
+
+  // Innermost matches (matches after any scheme or "www.") are better than
+  // non-innermost matches.
+  if (a.innermost_match != b.innermost_match)
+    return a.innermost_match;
+
+  // URLs that have been typed more often are better.
+  if (a.url_info.typed_count() != b.url_info.typed_count())
+    return a.url_info.typed_count() > b.url_info.typed_count();
+
+  // For URLs that have each been typed once, a host (alone) is better than a
+  // page inside.
+  if ((a.url_info.typed_count() == 1) && (a.IsHostOnly() != b.IsHostOnly()))
+    return a.IsHostOnly();
+
+  // URLs that have been visited more often are better.
+  if (a.url_info.visit_count() != b.url_info.visit_count())
+    return a.url_info.visit_count() > b.url_info.visit_count();
+
+  // URLs that have been visited more recently are better.
+  return a.url_info.last_visit() > b.url_info.last_visit();
+}
+
+// Sorts and dedups the given list of matches.
+void SortAndDedupMatches(history::HistoryMatches* matches) {
+  // Sort by quality, best first.
+  std::sort(matches->begin(), matches->end(), &CompareHistoryMatch);
+
+  // Remove duplicate matches (caused by the search string appearing in one of
+  // the prefixes as well as after it).  Consider the following scenario:
+  //
+  // User has visited "http://http.com" once and "http://htaccess.com" twice.
+  // User types "http".  The autocomplete search with prefix "http://" returns
+  // the first host, while the search with prefix "" returns both hosts.  Now
+  // we sort them into rank order:
+  //   http://http.com     (innermost_match)
+  //   http://htaccess.com (!innermost_match, url_info.visit_count == 2)
+  //   http://http.com     (!innermost_match, url_info.visit_count == 1)
+  //
+  // The above scenario tells us we can't use std::unique(), since our
+  // duplicates are not always sequential.  It also tells us we should remove
+  // the lower-quality duplicate(s), since otherwise the returned results won't
+  // be ordered correctly.  This is easy to do: we just always remove the later
+  // element of a duplicate pair.
+  // Be careful!  Because the vector contents may change as we remove elements,
+  // we use an index instead of an iterator in the outer loop, and don't
+  // precalculate the ending position.
+  for (size_t i = 0; i < matches->size(); ++i) {
+    for (history::HistoryMatches::iterator j(matches->begin() + i + 1);
+         j != matches->end(); ) {
+      if ((*matches)[i].url_info.url() == j->url_info.url())
+        j = matches->erase(j);
+      else
+        ++j;
+    }
+  }
+}
+
+// Calculates a new relevance score applying half-life time decaying to |count|
+// using |time_since_last_visit| and |score_buckets|.  This function will never
+// return a score higher than |undecayed_relevance|; in other words, it can only
+// demote the old score.
+double CalculateRelevanceUsingScoreBuckets(
+    const HUPScoringParams::ScoreBuckets& score_buckets,
+    const base::TimeDelta& time_since_last_visit,
+    int undecayed_relevance,
+    int count) {
+  // Back off if above relevance cap.
+  if ((score_buckets.relevance_cap() != -1) &&
+      (undecayed_relevance >= score_buckets.relevance_cap()))
+    return undecayed_relevance;
+
+  // Time based decay using half-life time.
+  double decayed_count = count;
+  if (decayed_count > 0)
+    decayed_count *= score_buckets.HalfLifeTimeDecay(time_since_last_visit);
+
+  // Find a threshold where decayed_count >= bucket.
+  const HUPScoringParams::ScoreBuckets::CountMaxRelevance* score_bucket = NULL;
+  for (size_t i = 0; i < score_buckets.buckets().size(); ++i) {
+    score_bucket = &score_buckets.buckets()[i];
+    if (decayed_count >= score_bucket->first)
+      break;  // Buckets are in descending order, so we can ignore the rest.
+  }
+
+  return (score_bucket && (undecayed_relevance > score_bucket->second)) ?
+      score_bucket->second : undecayed_relevance;
+}
+
+// Returns a new relevance score for the given |match| based on the
+// |old_relevance| score and |scoring_params|.  The new relevance score is
+// guaranteed to be less than or equal to |old_relevance|.  In other words, this
+// function can only demote a score, never boost it.  Returns |old_relevance| if
+// experimental scoring is disabled.
+int CalculateRelevanceScoreUsingScoringParams(
+    const history::HistoryMatch& match,
+    int old_relevance,
+    const HUPScoringParams& scoring_params) {
+  if (!scoring_params.experimental_scoring_enabled)
+    return old_relevance;
+
+  const base::TimeDelta time_since_last_visit =
+      base::Time::Now() - match.url_info.last_visit();
+
+  int relevance = CalculateRelevanceUsingScoreBuckets(
+      scoring_params.typed_count_buckets, time_since_last_visit, old_relevance,
+      match.url_info.typed_count());
+
+  // Additional demotion (on top of typed_count demotion) of URLs that were
+  // never typed.
+  if (match.url_info.typed_count() == 0) {
+    relevance = CalculateRelevanceUsingScoreBuckets(
+        scoring_params.visited_count_buckets, time_since_last_visit, relevance,
+        match.url_info.visit_count());
+  }
+
+  DCHECK_LE(relevance, old_relevance);
+  return relevance;
+}
+
+// Extracts typed_count, visit_count, and last_visited time from the URLRow and
+// puts them in the additional info field of the |match| for display in
+// about:omnibox.
+void RecordAdditionalInfoFromUrlRow(const history::URLRow& info,
+                                    AutocompleteMatch* match) {
+  match->RecordAdditionalInfo("typed count", info.typed_count());
+  match->RecordAdditionalInfo("visit count", info.visit_count());
+  match->RecordAdditionalInfo("last visit", info.last_visit());
+}
+
+// If |create_if_necessary| is true, ensures that |matches| contains an entry
+// for |info|, creating a new such entry if necessary (using |input_location|
+// and |match_in_scheme|).
+//
+// If |promote| is true, this also ensures the entry is the first element in
+// |matches|, moving or adding it to the front as appropriate.  When |promote|
+// is false, existing matches are left in place, and newly added matches are
+// placed at the back.
+//
+// It's OK to call this function with both |create_if_necessary| and |promote|
+// false, in which case we'll do nothing.
+//
+// Returns whether the match exists regardless if it was promoted/created.
+bool CreateOrPromoteMatch(const history::URLRow& info,
+                          size_t input_location,
+                          bool match_in_scheme,
+                          history::HistoryMatches* matches,
+                          bool create_if_necessary,
+                          bool promote) {
+  // |matches| may already have an entry for this.
+  for (history::HistoryMatches::iterator i(matches->begin());
+       i != matches->end(); ++i) {
+    if (i->url_info.url() == info.url()) {
+      // Rotate it to the front if the caller wishes.
+      if (promote)
+        std::rotate(matches->begin(), i, i + 1);
+      return true;
+    }
+  }
+
+  if (!create_if_necessary)
+    return false;
+
+  // No entry, so create one.
+  history::HistoryMatch match(info, input_location, match_in_scheme, true);
+  if (promote)
+    matches->push_front(match);
+  else
+    matches->push_back(match);
+
+  return true;
+}
+
+// Returns whether |match| is suitable for inline autocompletion.
+bool CanPromoteMatchForInlineAutocomplete(const history::HistoryMatch& match) {
+  // We can promote this match if it's been typed at least n times, where n == 1
+  // for "simple" (host-only) URLs and n == 2 for others.  We set a higher bar
+  // for these long URLs because it's less likely that users will want to visit
+  // them again.  Even though we don't increment the typed_count for pasted-in
+  // URLs, if the user manually edits the URL or types some long thing in by
+  // hand, we wouldn't want to immediately start autocompleting it.
+  return match.url_info.typed_count() &&
+      ((match.url_info.typed_count() > 1) || match.IsHostOnly());
+}
+
+// Given the user's |input| and a |match| created from it, reduce the match's
+// URL to just a host.  If this host still matches the user input, return it.
+// Returns the empty string on failure.
+GURL ConvertToHostOnly(const history::HistoryMatch& match,
+                       const base::string16& input) {
+  // See if we should try to do host-only suggestions for this URL. Nonstandard
+  // schemes means there's no authority section, so suggesting the host name
+  // is useless. File URLs are standard, but host suggestion is not useful for
+  // them either.
+  const GURL& url = match.url_info.url();
+  if (!url.is_valid() || !url.IsStandard() || url.SchemeIsFile())
+    return GURL();
+
+  // Transform to a host-only match.  Bail if the host no longer matches the
+  // user input (e.g. because the user typed more than just a host).
+  GURL host = url.GetWithEmptyPath();
+  if ((host.spec().length() < (match.input_location + input.length())))
+    return GURL();  // User typing is longer than this host suggestion.
+
+  const base::string16 spec = base::UTF8ToUTF16(host.spec());
+  if (spec.compare(match.input_location, input.length(), input))
+    return GURL();  // User typing is no longer a prefix.
+
+  return host;
+}
+
+}  // namespace
+
+// -----------------------------------------------------------------
+// SearchTermsDataSnapshot
+
+// Implementation of SearchTermsData that takes a snapshot of another
+// SearchTermsData by copying all the responses to the different getters into
+// member strings, then returning those strings when its own getters are called.
+// This will typically be constructed on the UI thread from
+// UIThreadSearchTermsData but is subsequently safe to use on any thread.
+class SearchTermsDataSnapshot : public SearchTermsData {
+ public:
+  explicit SearchTermsDataSnapshot(const SearchTermsData& search_terms_data);
+  ~SearchTermsDataSnapshot() override;
+
+  std::string GoogleBaseURLValue() const override;
+  std::string GetApplicationLocale() const override;
+  base::string16 GetRlzParameterValue(bool from_app_list) const override;
+  std::string GetSearchClient() const override;
+  bool EnableAnswersInSuggest() const override;
+  bool IsShowingSearchTermsOnSearchResultsPages() const override;
+  std::string InstantExtendedEnabledParam(bool for_search) const override;
+  std::string ForceInstantResultsParam(bool for_prerender) const override;
+  std::string NTPIsThemedParam() const override;
+  std::string GoogleImageSearchSource() const override;
+
+ private:
+  std::string google_base_url_value_;
+  std::string application_locale_;
+  base::string16 rlz_parameter_value_;
+  std::string search_client_;
+  bool enable_answers_in_suggest_;
+  bool is_showing_search_terms_on_search_results_pages_;
+  std::string instant_extended_enabled_param_;
+  std::string instant_extended_enabled_param_for_search_;
+  std::string force_instant_results_param_;
+  std::string force_instant_results_param_for_prerender_;
+  std::string ntp_is_themed_param_;
+  std::string google_image_search_source_;
+
+  DISALLOW_COPY_AND_ASSIGN(SearchTermsDataSnapshot);
+};
+
+SearchTermsDataSnapshot::SearchTermsDataSnapshot(
+    const SearchTermsData& search_terms_data)
+    : google_base_url_value_(search_terms_data.GoogleBaseURLValue()),
+      application_locale_(search_terms_data.GetApplicationLocale()),
+      rlz_parameter_value_(search_terms_data.GetRlzParameterValue(false)),
+      search_client_(search_terms_data.GetSearchClient()),
+      enable_answers_in_suggest_(search_terms_data.EnableAnswersInSuggest()),
+      is_showing_search_terms_on_search_results_pages_(
+          search_terms_data.IsShowingSearchTermsOnSearchResultsPages()),
+      instant_extended_enabled_param_(
+          search_terms_data.InstantExtendedEnabledParam(false)),
+      instant_extended_enabled_param_for_search_(
+          search_terms_data.InstantExtendedEnabledParam(true)),
+      force_instant_results_param_(
+          search_terms_data.ForceInstantResultsParam(false)),
+      force_instant_results_param_for_prerender_(
+          search_terms_data.ForceInstantResultsParam(true)),
+      ntp_is_themed_param_(search_terms_data.NTPIsThemedParam()),
+      google_image_search_source_(search_terms_data.GoogleImageSearchSource()) {
+}
+
+SearchTermsDataSnapshot::~SearchTermsDataSnapshot() {
+}
+
+std::string SearchTermsDataSnapshot::GoogleBaseURLValue() const {
+  return google_base_url_value_;
+}
+
+std::string SearchTermsDataSnapshot::GetApplicationLocale() const {
+  return application_locale_;
+}
+
+base::string16 SearchTermsDataSnapshot::GetRlzParameterValue(
+    bool from_app_list) const {
+  return rlz_parameter_value_;
+}
+
+std::string SearchTermsDataSnapshot::GetSearchClient() const {
+  return search_client_;
+}
+
+bool SearchTermsDataSnapshot::EnableAnswersInSuggest() const {
+  return enable_answers_in_suggest_;
+}
+
+bool SearchTermsDataSnapshot::IsShowingSearchTermsOnSearchResultsPages() const {
+  return is_showing_search_terms_on_search_results_pages_;
+}
+
+std::string SearchTermsDataSnapshot::InstantExtendedEnabledParam(
+    bool for_search) const {
+  return for_search ? instant_extended_enabled_param_ :
+      instant_extended_enabled_param_for_search_;
+}
+
+std::string SearchTermsDataSnapshot::ForceInstantResultsParam(
+    bool for_prerender) const {
+  return for_prerender ? force_instant_results_param_ :
+      force_instant_results_param_for_prerender_;
+}
+
+std::string SearchTermsDataSnapshot::NTPIsThemedParam() const {
+  return ntp_is_themed_param_;
+}
+
+std::string SearchTermsDataSnapshot::GoogleImageSearchSource() const {
+  return google_image_search_source_;
+}
+
+// -----------------------------------------------------------------
+// HistoryURLProvider
+
+// These ugly magic numbers will go away once we switch all scoring
+// behavior (including URL-what-you-typed) to HistoryQuick provider.
+const int HistoryURLProvider::kScoreForBestInlineableResult = 1413;
+const int HistoryURLProvider::kScoreForUnvisitedIntranetResult = 1403;
+const int HistoryURLProvider::kScoreForWhatYouTypedResult = 1203;
+const int HistoryURLProvider::kBaseScoreForNonInlineableResult = 900;
+
+// VisitClassifier is used to classify the type of visit to a particular url.
+class HistoryURLProvider::VisitClassifier {
+ public:
+  enum Type {
+    INVALID,             // Navigations to the URL are not allowed.
+    UNVISITED_INTRANET,  // A navigable URL for which we have no visit data but
+                         // which is known to refer to a visited intranet host.
+    VISITED,             // The site has been previously visited.
+  };
+
+  VisitClassifier(HistoryURLProvider* provider,
+                  const AutocompleteInput& input,
+                  history::URLDatabase* db);
+
+  // Returns the type of visit for the specified input.
+  Type type() const { return type_; }
+
+  // Returns the URLRow for the visit.
+  const history::URLRow& url_row() const { return url_row_; }
+
+ private:
+  HistoryURLProvider* provider_;
+  history::URLDatabase* db_;
+  Type type_;
+  history::URLRow url_row_;
+
+  DISALLOW_COPY_AND_ASSIGN(VisitClassifier);
+};
+
+HistoryURLProvider::VisitClassifier::VisitClassifier(
+    HistoryURLProvider* provider,
+    const AutocompleteInput& input,
+    history::URLDatabase* db)
+    : provider_(provider),
+      db_(db),
+      type_(INVALID) {
+  const GURL& url = input.canonicalized_url();
+  // Detect email addresses.  These cases will look like "http://user@site/",
+  // and because the history backend strips auth creds, we'll get a bogus exact
+  // match below if the user has visited "site".
+  if (!url.is_valid() ||
+      ((input.type() == metrics::OmniboxInputType::UNKNOWN) &&
+       input.parts().username.is_nonempty() &&
+       !input.parts().password.is_nonempty() &&
+       !input.parts().path.is_nonempty()))
+    return;
+
+  if (db_->GetRowForURL(url, &url_row_)) {
+    type_ = VISITED;
+    return;
+  }
+
+  if (provider_->CanFindIntranetURL(db_, input)) {
+    // The user typed an intranet hostname that they've visited (albeit with a
+    // different port and/or path) before.
+    url_row_ = history::URLRow(url);
+    type_ = UNVISITED_INTRANET;
+  }
+}
+
+HistoryURLProviderParams::HistoryURLProviderParams(
+    const AutocompleteInput& input,
+    bool trim_http,
+    const AutocompleteMatch& what_you_typed_match,
+    const std::string& languages,
+    TemplateURL* default_search_provider,
+    const SearchTermsData& search_terms_data)
+    : message_loop(base::MessageLoop::current()),
+      input(input),
+      prevent_inline_autocomplete(input.prevent_inline_autocomplete()),
+      trim_http(trim_http),
+      what_you_typed_match(what_you_typed_match),
+      failed(false),
+      exact_suggestion_is_in_history(false),
+      promote_type(NEITHER),
+      languages(languages),
+      default_search_provider(default_search_provider ?
+          new TemplateURL(default_search_provider->data()) : NULL),
+      search_terms_data(new SearchTermsDataSnapshot(search_terms_data)) {
+}
+
+HistoryURLProviderParams::~HistoryURLProviderParams() {
+}
+
+HistoryURLProvider::HistoryURLProvider(AutocompleteProviderClient* client,
+                                       AutocompleteProviderListener* listener)
+    : HistoryProvider(AutocompleteProvider::TYPE_HISTORY_URL, client),
+      listener_(listener),
+      params_(NULL) {
+  // Initialize HUP scoring params based on the current experiment.
+  OmniboxFieldTrial::GetExperimentalHUPScoringParams(&scoring_params_);
+}
+
+void HistoryURLProvider::Start(const AutocompleteInput& input,
+                               bool minimal_changes,
+                               bool called_due_to_focus) {
+  // NOTE: We could try hard to do less work in the |minimal_changes| case
+  // here; some clever caching would let us reuse the raw matches from the
+  // history DB without re-querying.  However, we'd still have to go back to
+  // the history thread to mark these up properly, and if pass 2 is currently
+  // running, we'd need to wait for it to return to the main thread before
+  // doing this (we can't just write new data for it to read due to thread
+  // safety issues).  At that point it's just as fast, and easier, to simply
+  // re-run the query from scratch and ignore |minimal_changes|.
+
+  // Cancel any in-progress query.
+  Stop(false, false);
+
+  matches_.clear();
+
+  if (called_due_to_focus ||
+      (input.type() == metrics::OmniboxInputType::INVALID) ||
+      (input.type() == metrics::OmniboxInputType::FORCED_QUERY))
+    return;
+
+  // Do some fixup on the user input before matching against it, so we provide
+  // good results for local file paths, input with spaces, etc.
+  const FixupReturn fixup_return(FixupUserInput(input));
+  if (!fixup_return.first)
+    return;
+  url::Parsed parts;
+  url_fixer::SegmentURL(fixup_return.second, &parts);
+  AutocompleteInput fixed_up_input(input);
+  fixed_up_input.UpdateText(fixup_return.second, base::string16::npos, parts);
+
+  // Create a match for what the user typed.
+  const bool trim_http = !AutocompleteInput::HasHTTPScheme(input.text());
+  AutocompleteMatch what_you_typed_match(SuggestExactInput(
+      fixed_up_input.text(), fixed_up_input.canonicalized_url(), trim_http));
+  what_you_typed_match.relevance = CalculateRelevance(WHAT_YOU_TYPED, 0);
+
+  // Add the WYT match as a fallback in case we can't get the history service or
+  // URL DB; otherwise, we'll replace this match lower down.  Don't do this for
+  // queries, though -- while we can sometimes mark up a match for them, it's
+  // not what the user wants, and just adds noise.
+  if (fixed_up_input.type() != metrics::OmniboxInputType::QUERY)
+    matches_.push_back(what_you_typed_match);
+
+  // We'll need the history service to run both passes, so try to obtain it.
+  history::HistoryService* const history_service = client()->HistoryService();
+  if (!history_service)
+    return;
+
+  // Get the default search provider and search terms data now since we have to
+  // retrieve these on the UI thread, and the second pass runs on the history
+  // thread. |template_url_service| can be NULL when testing.
+  TemplateURLService* template_url_service = client()->GetTemplateURLService();
+  TemplateURL* default_search_provider = template_url_service ?
+      template_url_service->GetDefaultSearchProvider() : NULL;
+
+  // Create the data structure for the autocomplete passes.  We'll save this off
+  // onto the |params_| member for later deletion below if we need to run pass
+  // 2.
+  scoped_ptr<HistoryURLProviderParams> params(new HistoryURLProviderParams(
+      fixed_up_input, trim_http, what_you_typed_match,
+      client()->AcceptLanguages(), default_search_provider,
+      client()->GetSearchTermsData()));
+  // Note that we use the non-fixed-up input here, since fixup may strip
+  // trailing whitespace.
+  params->prevent_inline_autocomplete = PreventInlineAutocomplete(input);
+
+  // Pass 1: Get the in-memory URL database, and use it to find and promote
+  // the inline autocomplete match, if any.
+  history::URLDatabase* url_db = history_service->InMemoryDatabase();
+  // url_db can be NULL if it hasn't finished initializing (or failed to
+  // initialize).  In this case all we can do is fall back on the second
+  // pass.
+  //
+  // TODO(pkasting): We should just block here until this loads.  Any time
+  // someone unloads the history backend, we'll get inconsistent inline
+  // autocomplete behavior here.
+  if (url_db) {
+    DoAutocomplete(NULL, url_db, params.get());
+    matches_.clear();
+    PromoteMatchesIfNecessary(*params);
+    // NOTE: We don't reset |params| here since at least the |promote_type|
+    // field on it will be read by the second pass -- see comments in
+    // DoAutocomplete().
+  }
+
+  // Pass 2: Ask the history service to call us back on the history thread,
+  // where we can read the full on-disk DB.
+  if (input.want_asynchronous_matches()) {
+    done_ = false;
+    params_ = params.release();  // This object will be destroyed in
+                                 // QueryComplete() once we're done with it.
+    history_service->ScheduleAutocomplete(
+        base::Bind(&HistoryURLProvider::ExecuteWithDB, this, params_));
+  }
+}
+
+void HistoryURLProvider::Stop(bool clear_cached_results,
+                              bool due_to_user_inactivity) {
+  done_ = true;
+
+  if (params_)
+    params_->cancel_flag.Set();
+}
+
+AutocompleteMatch HistoryURLProvider::SuggestExactInput(
+    const base::string16& text,
+    const GURL& destination_url,
+    bool trim_http) {
+  // The FormattedStringWithEquivalentMeaning() call below requires callers to
+  // be on the main thread.
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  AutocompleteMatch match(this, 0, false,
+                          AutocompleteMatchType::URL_WHAT_YOU_TYPED);
+
+  if (destination_url.is_valid()) {
+    match.destination_url = destination_url;
+
+    // Trim off "http://" if the user didn't type it.
+    DCHECK(!trim_http || !AutocompleteInput::HasHTTPScheme(text));
+    base::string16 display_string(
+        net::FormatUrl(destination_url, std::string(),
+                       net::kFormatUrlOmitAll & ~net::kFormatUrlOmitHTTP,
+                       net::UnescapeRule::SPACES, NULL, NULL, NULL));
+    const size_t offset = trim_http ? TrimHttpPrefix(&display_string) : 0;
+    match.fill_into_edit =
+        AutocompleteInput::FormattedStringWithEquivalentMeaning(
+            destination_url, display_string, client()->SchemeClassifier());
+    match.allowed_to_be_default_match = true;
+    // NOTE: Don't set match.inline_autocompletion to something non-empty here;
+    // it's surprising and annoying.
+
+    // Try to highlight "innermost" match location.  If we fix up "w" into
+    // "www.w.com", we want to highlight the fifth character, not the first.
+    // This relies on match.destination_url being the non-prefix-trimmed version
+    // of match.contents.
+    match.contents = display_string;
+    const URLPrefix* best_prefix = URLPrefix::BestURLPrefix(
+        base::UTF8ToUTF16(destination_url.spec()), text);
+    // It's possible for match.destination_url to not contain the user's input
+    // at all (so |best_prefix| is NULL), for example if the input is
+    // "view-source:x" and |destination_url| has an inserted "http://" in the
+    // middle.
+    if (best_prefix == NULL) {
+      AutocompleteMatch::ClassifyMatchInString(text, match.contents,
+                                               ACMatchClassification::URL,
+                                               &match.contents_class);
+    } else {
+      AutocompleteMatch::ClassifyLocationInString(
+          best_prefix->prefix.length() - offset, text.length(),
+          match.contents.length(), ACMatchClassification::URL,
+          &match.contents_class);
+    }
+  }
+
+  return match;
+}
+
+void HistoryURLProvider::ExecuteWithDB(HistoryURLProviderParams* params,
+                                       history::HistoryBackend* backend,
+                                       history::URLDatabase* db) {
+  // We may get called with a NULL database if it couldn't be properly
+  // initialized.
+  if (!db) {
+    params->failed = true;
+  } else if (!params->cancel_flag.IsSet()) {
+    base::TimeTicks beginning_time = base::TimeTicks::Now();
+
+    DoAutocomplete(backend, db, params);
+
+    UMA_HISTOGRAM_TIMES("Autocomplete.HistoryAsyncQueryTime",
+                        base::TimeTicks::Now() - beginning_time);
+  }
+
+  // Return the results (if any) to the main thread.
+  params->message_loop->task_runner()->PostTask(
+      FROM_HERE, base::Bind(&HistoryURLProvider::QueryComplete, this, params));
+}
+
+HistoryURLProvider::~HistoryURLProvider() {
+  // Note: This object can get leaked on shutdown if there are pending
+  // requests on the database (which hold a reference to us). Normally, these
+  // messages get flushed for each thread. We do a round trip from main, to
+  // history, back to main while holding a reference. If the main thread
+  // completes before the history thread, the message to delegate back to the
+  // main thread will not run and the reference will leak. Therefore, don't do
+  // anything on destruction.
+}
+
+// static
+int HistoryURLProvider::CalculateRelevance(MatchType match_type,
+                                           int match_number) {
+  switch (match_type) {
+    case INLINE_AUTOCOMPLETE:
+      return kScoreForBestInlineableResult;
+
+    case UNVISITED_INTRANET:
+      return kScoreForUnvisitedIntranetResult;
+
+    case WHAT_YOU_TYPED:
+      return kScoreForWhatYouTypedResult;
+
+    default:  // NORMAL
+      return kBaseScoreForNonInlineableResult + match_number;
+  }
+}
+
+// static
+ACMatchClassifications HistoryURLProvider::ClassifyDescription(
+    const base::string16& input_text,
+    const base::string16& description) {
+  base::string16 clean_description =
+      bookmarks::CleanUpTitleForMatching(description);
+  TermMatches description_matches(SortAndDeoverlapMatches(
+      MatchTermInString(input_text, clean_description, 0)));
+  WordStarts description_word_starts;
+  String16VectorFromString16(clean_description, false,
+                             &description_word_starts);
+  // If HistoryURL retrieves any matches (and hence we reach this code), we
+  // are guaranteed that the beginning of input_text must be a word break.
+  WordStarts offsets(1, 0u);
+  description_matches = ScoredHistoryMatch::FilterTermMatchesByWordStarts(
+      description_matches, offsets, description_word_starts, 0,
+      std::string::npos);
+  return SpansFromTermMatch(
+      description_matches, clean_description.length(), false);
+}
+
+void HistoryURLProvider::DoAutocomplete(history::HistoryBackend* backend,
+                                        history::URLDatabase* db,
+                                        HistoryURLProviderParams* params) {
+  // Get the matching URLs from the DB.
+  params->matches.clear();
+  history::URLRows url_matches;
+  const URLPrefixes& prefixes = URLPrefix::GetURLPrefixes();
+  for (URLPrefixes::const_iterator i(prefixes.begin()); i != prefixes.end();
+       ++i) {
+    if (params->cancel_flag.IsSet())
+      return;  // Canceled in the middle of a query, give up.
+
+    // We only need kMaxMatches results in the end, but before we get there we
+    // need to promote lower-quality matches that are prefixes of higher-quality
+    // matches, and remove lower-quality redirects.  So we ask for more results
+    // than we need, of every prefix type, in hopes this will give us far more
+    // than enough to work with.  CullRedirects() will then reduce the list to
+    // the best kMaxMatches results.
+    db->AutocompleteForPrefix(
+        base::UTF16ToUTF8(i->prefix + params->input.text()), kMaxMatches * 2,
+        !backend, &url_matches);
+    for (history::URLRows::const_iterator j(url_matches.begin());
+          j != url_matches.end(); ++j) {
+      const URLPrefix* best_prefix = URLPrefix::BestURLPrefix(
+          base::UTF8ToUTF16(j->url().spec()), base::string16());
+      DCHECK(best_prefix);
+      params->matches.push_back(history::HistoryMatch(
+          *j, i->prefix.length(), !i->num_components,
+          i->num_components >= best_prefix->num_components));
+    }
+  }
+
+  // Create sorted list of suggestions.
+  CullPoorMatches(params);
+  SortAndDedupMatches(&params->matches);
+
+  // Try to create a shorter suggestion from the best match.
+  // We consider the what you typed match eligible for display when it's
+  // navigable and there's a reasonable chance the user intended to do
+  // something other than search.  We use a variety of heuristics to determine
+  // this, e.g. whether the user explicitly typed a scheme, or if omnibox
+  // searching has been disabled by policy. In the cases where we've parsed as
+  // UNKNOWN, we'll still show an accidental search infobar if need be.
+  VisitClassifier classifier(this, params->input, db);
+  params->have_what_you_typed_match =
+      (params->input.type() != metrics::OmniboxInputType::QUERY) &&
+      ((params->input.type() != metrics::OmniboxInputType::UNKNOWN) ||
+       (classifier.type() == VisitClassifier::UNVISITED_INTRANET) ||
+       !params->trim_http ||
+       (AutocompleteInput::NumNonHostComponents(params->input.parts()) > 0) ||
+       !params->default_search_provider);
+  const bool have_shorter_suggestion_suitable_for_inline_autocomplete =
+      PromoteOrCreateShorterSuggestion(db, params);
+
+  // Check whether what the user typed appears in history.
+  const bool can_check_history_for_exact_match =
+      // Checking what_you_typed_match.allowed_to_be_default_match tells us
+      // whether SuggestExactInput() succeeded in constructing a valid match.
+      params->what_you_typed_match.allowed_to_be_default_match &&
+      // Additionally, in the case where the user has typed "foo.com" and
+      // visited (but not typed) "foo/", and the input is "foo", the first pass
+      // will fall into the FRONT_HISTORY_MATCH case for "foo.com" but the
+      // second pass can suggest the exact input as a better URL.  Since we need
+      // both passes to agree, and since during the first pass there's no way to
+      // know about "foo/", ensure that if the promote type was set to
+      // FRONT_HISTORY_MATCH during the first pass, the second pass will not
+      // consider the exact suggestion to be in history and therefore will not
+      // suggest the exact input as a better match.  (Note that during the first
+      // pass, this conditional will always succeed since |promote_type| is
+      // initialized to NEITHER.)
+      (params->promote_type != HistoryURLProviderParams::FRONT_HISTORY_MATCH);
+  params->exact_suggestion_is_in_history = can_check_history_for_exact_match &&
+      FixupExactSuggestion(db, classifier, params);
+
+  // If we succeeded in fixing up the exact match based on the user's history,
+  // we should treat it as the best match regardless of input type.  If not,
+  // then we check whether there's an inline autocompletion we can create from
+  // this input, so we can promote that as the best match.
+  if (params->exact_suggestion_is_in_history) {
+    params->promote_type = HistoryURLProviderParams::WHAT_YOU_TYPED_MATCH;
+  } else if (!params->matches.empty() &&
+             (have_shorter_suggestion_suitable_for_inline_autocomplete ||
+              CanPromoteMatchForInlineAutocomplete(params->matches[0]))) {
+    // Note that we promote this inline-autocompleted match even when
+    // params->prevent_inline_autocomplete is true.  This is safe because in
+    // this case the match will be marked as "not allowed to be default", and
+    // a non-inlined match that is "allowed to be default" will be reordered
+    // above it by the controller/AutocompleteResult.  We ensure there is such
+    // a match in two ways:
+    //   * If params->have_what_you_typed_match is true, we force the
+    //     what-you-typed match to be added in this case.  See comments in
+    //     PromoteMatchesIfNecessary().
+    //   * Otherwise, we should have some sort of QUERY or UNKNOWN input that
+    //     the SearchProvider will provide a defaultable WYT match for.
+    params->promote_type = HistoryURLProviderParams::FRONT_HISTORY_MATCH;
+  } else {
+    // Failed to promote any URLs.  Use the What You Typed match, if we have it.
+    params->promote_type = params->have_what_you_typed_match ?
+        HistoryURLProviderParams::WHAT_YOU_TYPED_MATCH :
+        HistoryURLProviderParams::NEITHER;
+  }
+
+  const size_t max_results =
+      kMaxMatches + (params->exact_suggestion_is_in_history ? 1 : 0);
+  if (backend) {
+    // Remove redirects and trim list to size.  We want to provide up to
+    // kMaxMatches results plus the What You Typed result, if it was added to
+    // params->matches above.
+    CullRedirects(backend, &params->matches, max_results);
+  } else if (params->matches.size() > max_results) {
+    // Simply trim the list to size.
+    params->matches.resize(max_results);
+  }
+}
+
+void HistoryURLProvider::PromoteMatchesIfNecessary(
+    const HistoryURLProviderParams& params) {
+  if (params.promote_type == HistoryURLProviderParams::NEITHER)
+    return;
+  if (params.promote_type == HistoryURLProviderParams::FRONT_HISTORY_MATCH) {
+    matches_.push_back(
+        HistoryMatchToACMatch(params, 0, INLINE_AUTOCOMPLETE,
+                              CalculateRelevance(INLINE_AUTOCOMPLETE, 0)));
+  }
+  // There are two cases where we need to add the what-you-typed-match:
+  //   * If params.promote_type is WHAT_YOU_TYPED_MATCH, we're being explicitly
+  //     directed to.
+  //   * If params.have_what_you_typed_match is true, then params.promote_type
+  //     can't be NEITHER (see code near the end of DoAutocomplete()), so if
+  //     it's not WHAT_YOU_TYPED_MATCH, it must be FRONT_HISTORY_MATCH, and
+  //     we'll have promoted the history match above.  If
+  //     params.prevent_inline_autocomplete is also true, then this match
+  //     will be marked "not allowed to be default", and we need to add the
+  //     what-you-typed match to ensure there's a legal default match for the
+  //     controller/AutocompleteResult to promote.  (If
+  //     params.have_what_you_typed_match is false, the SearchProvider should
+  //     take care of adding this defaultable match.)
+  if ((params.promote_type == HistoryURLProviderParams::WHAT_YOU_TYPED_MATCH) ||
+      (params.prevent_inline_autocomplete &&
+       params.have_what_you_typed_match)) {
+    matches_.push_back(params.what_you_typed_match);
+  }
+}
+
+void HistoryURLProvider::QueryComplete(
+    HistoryURLProviderParams* params_gets_deleted) {
+  // Ensure |params_gets_deleted| gets deleted on exit.
+  scoped_ptr<HistoryURLProviderParams> params(params_gets_deleted);
+
+  // If the user hasn't already started another query, clear our member pointer
+  // so we can't write into deleted memory.
+  if (params_ == params_gets_deleted)
+    params_ = NULL;
+
+  // Don't send responses for queries that have been canceled.
+  if (params->cancel_flag.IsSet())
+    return;  // Already set done_ when we canceled, no need to set it again.
+
+  // Don't modify |matches_| if the query failed, since it might have a default
+  // match in it, whereas |params->matches| will be empty.
+  if (!params->failed) {
+    matches_.clear();
+    PromoteMatchesIfNecessary(*params);
+
+    // Determine relevance of highest scoring match, if any.
+    int relevance = matches_.empty() ?
+        CalculateRelevance(NORMAL,
+                           static_cast<int>(params->matches.size() - 1)) :
+        matches_[0].relevance;
+
+    // Convert the history matches to autocomplete matches.  If we promoted the
+    // first match, skip over it.
+    const size_t first_match =
+        (params->exact_suggestion_is_in_history ||
+         (params->promote_type ==
+             HistoryURLProviderParams::FRONT_HISTORY_MATCH)) ? 1 : 0;
+    for (size_t i = first_match; i < params->matches.size(); ++i) {
+      // All matches score one less than the previous match.
+      --relevance;
+      // The experimental scoring must not change the top result's score.
+      if (!matches_.empty()) {
+        relevance = CalculateRelevanceScoreUsingScoringParams(
+            params->matches[i], relevance, scoring_params_);
+      }
+      matches_.push_back(HistoryMatchToACMatch(*params, i, NORMAL, relevance));
+    }
+  }
+
+  done_ = true;
+  listener_->OnProviderUpdate(true);
+}
+
+bool HistoryURLProvider::FixupExactSuggestion(
+    history::URLDatabase* db,
+    const VisitClassifier& classifier,
+    HistoryURLProviderParams* params) const {
+  MatchType type = INLINE_AUTOCOMPLETE;
+  switch (classifier.type()) {
+    case VisitClassifier::INVALID:
+      return false;
+    case VisitClassifier::UNVISITED_INTRANET:
+      type = UNVISITED_INTRANET;
+      break;
+    default:
+      DCHECK_EQ(VisitClassifier::VISITED, classifier.type());
+      // We have data for this match, use it.
+      params->what_you_typed_match.deletable = true;
+      params->what_you_typed_match.description = classifier.url_row().title();
+      RecordAdditionalInfoFromUrlRow(classifier.url_row(),
+                                     &params->what_you_typed_match);
+      params->what_you_typed_match.description_class = ClassifyDescription(
+          params->input.text(), params->what_you_typed_match.description);
+      if (!classifier.url_row().typed_count()) {
+        // If we reach here, we must be in the second pass, and we must not have
+        // this row's data available during the first pass.  That means we
+        // either scored it as WHAT_YOU_TYPED or UNVISITED_INTRANET, and to
+        // maintain the ordering between passes consistent, we need to score it
+        // the same way here.
+        type = CanFindIntranetURL(db, params->input) ?
+            UNVISITED_INTRANET : WHAT_YOU_TYPED;
+      }
+      break;
+  }
+
+  params->what_you_typed_match.relevance = CalculateRelevance(type, 0);
+
+  // If there are any other matches, then don't promote this match here, in
+  // hopes the caller will be able to inline autocomplete a better suggestion.
+  // DoAutocomplete() will fall back on this match if inline autocompletion
+  // fails.  This matches how we react to never-visited URL inputs in the non-
+  // intranet case.
+  if (type == UNVISITED_INTRANET && !params->matches.empty())
+    return false;
+
+  // Put it on the front of the HistoryMatches for redirect culling.
+  CreateOrPromoteMatch(classifier.url_row(), base::string16::npos, false,
+                       &params->matches, true, true);
+  return true;
+}
+
+bool HistoryURLProvider::CanFindIntranetURL(
+    history::URLDatabase* db,
+    const AutocompleteInput& input) const {
+  // Normally passing the first two conditions below ought to guarantee the
+  // third condition, but because FixupUserInput() can run and modify the
+  // input's text and parts between Parse() and here, it seems better to be
+  // paranoid and check.
+  if ((input.type() != metrics::OmniboxInputType::UNKNOWN) ||
+      !base::LowerCaseEqualsASCII(input.scheme(), url::kHttpScheme) ||
+      !input.parts().host.is_nonempty())
+    return false;
+  const std::string host(base::UTF16ToUTF8(
+      input.text().substr(input.parts().host.begin, input.parts().host.len)));
+  const size_t registry_length =
+      net::registry_controlled_domains::GetRegistryLength(
+          host,
+          net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES,
+          net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
+  return registry_length == 0 && db->IsTypedHost(host);
+}
+
+bool HistoryURLProvider::PromoteOrCreateShorterSuggestion(
+    history::URLDatabase* db,
+    HistoryURLProviderParams* params) {
+  if (params->matches.empty())
+    return false;  // No matches, nothing to do.
+
+  // Determine the base URL from which to search, and whether that URL could
+  // itself be added as a match.  We can add the base iff it's not "effectively
+  // the same" as any "what you typed" match.
+  const history::HistoryMatch& match = params->matches[0];
+  GURL search_base = ConvertToHostOnly(match, params->input.text());
+  bool can_add_search_base_to_matches = !params->have_what_you_typed_match;
+  if (search_base.is_empty()) {
+    // Search from what the user typed when we couldn't reduce the best match
+    // to a host.  Careful: use a substring of |match| here, rather than the
+    // first match in |params|, because they might have different prefixes.  If
+    // the user typed "google.com", params->what_you_typed_match will hold
+    // "http://google.com/", but |match| might begin with
+    // "http://www.google.com/".
+    // TODO: this should be cleaned up, and is probably incorrect for IDN.
+    std::string new_match = match.url_info.url().possibly_invalid_spec().
+        substr(0, match.input_location + params->input.text().length());
+    search_base = GURL(new_match);
+    if (search_base.is_empty())
+      return false;  // Can't construct a URL from which to start a search.
+  } else if (!can_add_search_base_to_matches) {
+    can_add_search_base_to_matches =
+        (search_base != params->what_you_typed_match.destination_url);
+  }
+  if (search_base == match.url_info.url())
+    return false;  // Couldn't shorten |match|, so no URLs to search over.
+
+  // Search the DB for short URLs between our base and |match|.
+  history::URLRow info(search_base);
+  bool promote = true;
+  // A short URL is only worth suggesting if it's been visited at least a third
+  // as often as the longer URL.
+  const int min_visit_count = ((match.url_info.visit_count() - 1) / 3) + 1;
+  // For stability between the in-memory and on-disk autocomplete passes, when
+  // the long URL has been typed before, only suggest shorter URLs that have
+  // also been typed.  Otherwise, the on-disk pass could suggest a shorter URL
+  // (which hasn't been typed) that the in-memory pass doesn't know about,
+  // thereby making the top match, and thus the behavior of inline
+  // autocomplete, unstable.
+  const int min_typed_count = match.url_info.typed_count() ? 1 : 0;
+  if (!db->FindShortestURLFromBase(search_base.possibly_invalid_spec(),
+          match.url_info.url().possibly_invalid_spec(), min_visit_count,
+          min_typed_count, can_add_search_base_to_matches, &info)) {
+    if (!can_add_search_base_to_matches)
+      return false;  // Couldn't find anything and can't add the search base.
+
+    // Try to get info on the search base itself.  Promote it to the top if the
+    // original best match isn't good enough to autocomplete.
+    db->GetRowForURL(search_base, &info);
+    promote = match.url_info.typed_count() <= 1;
+  }
+
+  // Promote or add the desired URL to the list of matches.
+  const bool ensure_can_inline =
+      promote && CanPromoteMatchForInlineAutocomplete(match);
+  return CreateOrPromoteMatch(info, match.input_location, match.match_in_scheme,
+                              &params->matches, true, promote) &&
+      ensure_can_inline;
+}
+
+void HistoryURLProvider::CullPoorMatches(
+    HistoryURLProviderParams* params) const {
+  const base::Time& threshold(history::AutocompleteAgeThreshold());
+  for (history::HistoryMatches::iterator i(params->matches.begin());
+       i != params->matches.end(); ) {
+    if (RowQualifiesAsSignificant(i->url_info, threshold) &&
+        (!params->default_search_provider ||
+         !params->default_search_provider->IsSearchURL(
+             i->url_info.url(), *params->search_terms_data))) {
+      ++i;
+    } else {
+      i = params->matches.erase(i);
+    }
+  }
+}
+
+void HistoryURLProvider::CullRedirects(history::HistoryBackend* backend,
+                                       history::HistoryMatches* matches,
+                                       size_t max_results) const {
+  for (size_t source = 0;
+       (source < matches->size()) && (source < max_results); ) {
+    const GURL& url = (*matches)[source].url_info.url();
+    // TODO(brettw) this should go away when everything uses GURL.
+    history::RedirectList redirects;
+    backend->QueryRedirectsFrom(url, &redirects);
+    if (!redirects.empty()) {
+      // Remove all but the first occurrence of any of these redirects in the
+      // search results. We also must add the URL we queried for, since it may
+      // not be the first match and we'd want to remove it.
+      //
+      // For example, when A redirects to B and our matches are [A, X, B],
+      // we'll get B as the redirects from, and we want to remove the second
+      // item of that pair, removing B. If A redirects to B and our matches are
+      // [B, X, A], we'll want to remove A instead.
+      redirects.push_back(url);
+      source = RemoveSubsequentMatchesOf(matches, source, redirects);
+    } else {
+      // Advance to next item.
+      source++;
+    }
+  }
+
+  if (matches->size() > max_results)
+    matches->resize(max_results);
+}
+
+size_t HistoryURLProvider::RemoveSubsequentMatchesOf(
+    history::HistoryMatches* matches,
+    size_t source_index,
+    const std::vector<GURL>& remove) const {
+  size_t next_index = source_index + 1;  // return value = item after source
+
+  // Find the first occurrence of any URL in the redirect chain. We want to
+  // keep this one since it is rated the highest.
+  history::HistoryMatches::iterator first(std::find_first_of(
+      matches->begin(), matches->end(), remove.begin(), remove.end(),
+      history::HistoryMatch::EqualsGURL));
+  DCHECK(first != matches->end()) << "We should have always found at least the "
+      "original URL.";
+
+  // Find any following occurrences of any URL in the redirect chain, these
+  // should be deleted.
+  for (history::HistoryMatches::iterator next(std::find_first_of(first + 1,
+           matches->end(), remove.begin(), remove.end(),
+           history::HistoryMatch::EqualsGURL));
+       next != matches->end(); next = std::find_first_of(next, matches->end(),
+           remove.begin(), remove.end(), history::HistoryMatch::EqualsGURL)) {
+    // Remove this item. When we remove an item before the source index, we
+    // need to shift it to the right and remember that so we can return it.
+    next = matches->erase(next);
+    if (static_cast<size_t>(next - matches->begin()) < next_index)
+      --next_index;
+  }
+  return next_index;
+}
+
+AutocompleteMatch HistoryURLProvider::HistoryMatchToACMatch(
+    const HistoryURLProviderParams& params,
+    size_t match_number,
+    MatchType match_type,
+    int relevance) {
+  // The FormattedStringWithEquivalentMeaning() call below requires callers to
+  // be on the main thread.
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  const history::HistoryMatch& history_match = params.matches[match_number];
+  const history::URLRow& info = history_match.url_info;
+  AutocompleteMatch match(this, relevance,
+      !!info.visit_count(), AutocompleteMatchType::HISTORY_URL);
+  match.typed_count = info.typed_count();
+  match.destination_url = info.url();
+  DCHECK(match.destination_url.is_valid());
+  size_t inline_autocomplete_offset =
+      history_match.input_location + params.input.text().length();
+  std::string languages = (match_type == WHAT_YOU_TYPED) ?
+      std::string() : params.languages;
+  const net::FormatUrlTypes format_types = net::kFormatUrlOmitAll &
+      ~((params.trim_http && !history_match.match_in_scheme) ?
+          0 : net::kFormatUrlOmitHTTP);
+  match.fill_into_edit =
+      AutocompleteInput::FormattedStringWithEquivalentMeaning(
+          info.url(), net::FormatUrl(info.url(), languages, format_types,
+                                     net::UnescapeRule::SPACES, NULL, NULL,
+                                     &inline_autocomplete_offset),
+          client()->SchemeClassifier());
+  if (!params.prevent_inline_autocomplete &&
+      (inline_autocomplete_offset != base::string16::npos)) {
+    DCHECK(inline_autocomplete_offset <= match.fill_into_edit.length());
+    match.inline_autocompletion =
+        match.fill_into_edit.substr(inline_autocomplete_offset);
+  }
+  // The latter part of the test effectively asks "is the inline completion
+  // empty?" (i.e., is this match effectively the what-you-typed match?).
+  match.allowed_to_be_default_match = !params.prevent_inline_autocomplete ||
+      ((inline_autocomplete_offset != base::string16::npos) &&
+       (inline_autocomplete_offset >= match.fill_into_edit.length()));
+
+  size_t match_start = history_match.input_location;
+  match.contents = net::FormatUrl(info.url(), languages,
+      format_types, net::UnescapeRule::SPACES, NULL, NULL, &match_start);
+  if ((match_start != base::string16::npos) &&
+      (inline_autocomplete_offset != base::string16::npos) &&
+      (inline_autocomplete_offset != match_start)) {
+    DCHECK(inline_autocomplete_offset > match_start);
+    AutocompleteMatch::ClassifyLocationInString(match_start,
+        inline_autocomplete_offset - match_start, match.contents.length(),
+        ACMatchClassification::URL, &match.contents_class);
+  } else {
+    AutocompleteMatch::ClassifyLocationInString(base::string16::npos, 0,
+        match.contents.length(), ACMatchClassification::URL,
+        &match.contents_class);
+  }
+  match.description = info.title();
+  match.description_class =
+      ClassifyDescription(params.input.text(), match.description);
+  RecordAdditionalInfoFromUrlRow(info, &match);
+  return match;
+}