[AiS] Provide Answers queries with a session token.

chrome/browser/autocomplete/search_provider.cc

 // Copyright 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/autocomplete/search_provider.h"
 
 #include <algorithm>
 #include <cmath>
 
+#include "base/base64.h"
 #include "base/callback.h"
+#include "base/command_line.h"
 #include "base/i18n/break_iterator.h"
 #include "base/i18n/case_conversion.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
+#include "base/rand_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/autocomplete_classifier.h"
 #include "chrome/browser/autocomplete/autocomplete_classifier_factory.h"
 #include "chrome/browser/autocomplete/autocomplete_provider_listener.h"
 #include "chrome/browser/autocomplete/autocomplete_result.h"
 #include "chrome/browser/autocomplete/keyword_provider.h"
 #include "chrome/browser/autocomplete/url_prefix.h"
 #include "chrome/browser/google/google_util.h"
 #include "chrome/browser/history/history_service.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/history/in_memory_database.h"
 #include "chrome/browser/metrics/variations/variations_http_header_provider.h"
 #include "chrome/browser/omnibox/omnibox_field_trial.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/search_engines/template_url_prepopulate_data.h"
 #include "chrome/browser/search_engines/template_url_service.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/browser/ui/search/instant_controller.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/user_metrics.h"
 #include "grit/generated_resources.h"
 #include "net/base/escape.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_util.h"
 #include "net/http/http_request_headers.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_status.h"
@@ skipping 583 matching lines @@
     int id,
     const TemplateURL* template_url,
     const AutocompleteInput& input) {
   if (!template_url || template_url->suggestions_url().empty())
     return NULL;
 
   // Bail if the suggestion URL is invalid with the given replacements.
   TemplateURLRef::SearchTermsArgs search_term_args(input.text());
   search_term_args.cursor_position = input.cursor_position();
   search_term_args.page_classification = input.current_page_classification();
+#if defined(OS_ANDROID)

[Peter Kasting, 2014/05/09 21:35:07]

Why is this ifdef necessary?  It seems harmless to run this code for other
platforms.

[groby-ooo-7-16, 2014/05/09 21:50:25]

That's because the switch is Android-only :) 

It looks like Answers in general will have a small code footprint, so unless
that raises serious concerns, I'll just make it a cross-platform flag.

Would you mind a follow-up CL, since there are still CLs in flight with #if
OS_ANDROID?

[Peter Kasting, 2014/05/09 22:29:24]

Fine with me.

+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableAnswersInSuggest))

[Peter Kasting, 2014/05/09 21:35:07]

Nit: Indent 4, not 8

[groby-ooo-7-16, 2014/05/09 22:18:09]

Done.

+    search_term_args.session_token = GetSessionToken();
+#endif
   GURL suggest_url(template_url->suggestions_url_ref().ReplaceSearchTerms(
       search_term_args));
   if (!suggest_url.is_valid())
     return NULL;
   // Send the current page URL if user setting and URL requirements are met and
   // the user is in the field trial.
   if (CanSendURL(current_page_url_, suggest_url, template_url,
                  input.current_page_classification(), profile_) &&
       OmniboxFieldTrial::InZeroSuggestAfterTypingFieldTrial()) {
     search_term_args.current_page_url = current_page_url_.spec();
@@ skipping 473 matching lines @@
   match.RecordAdditionalInfo(kShouldPrefetchKey, kFalse);
 
   return match;
 }
 
 void SearchProvider::UpdateDone() {
   // We're done when the timer isn't running, there are no suggest queries
   // pending, and we're not waiting on Instant.
   done_ = !timer_.IsRunning() && (suggest_results_pending_ == 0);
 }
+
+std::string SearchProvider::GetSessionToken() {
+  // Renew token if it expired.
+  if (base::Time::Now() > token_expiration_time_) {

[Peter Kasting, 2014/05/09 21:35:07]

Time::Now() can go backward (e.g. for DST), leaving you with the same token for
a long time.  Perhaps you want to use TimeTicks, which won't decrease.  (Even
that could cease to increment for arbitrarily long times while the computer is
suspended -- is that a problem?)

[groby-ooo-7-16, 2014/05/09 21:50:25]

I picked Time because it's not affected by suspension. Long-lived tokens are not
really an issue - the server-side cache will just expire anyways. The only
reason to expire the token quickly is to not tie together search query history
unnecessarily. I don't think if it's an hour on rare cases causes significant
issues there.

[groby-ooo-7-16, 2014/05/09 22:18:09]

Done - TimeTicks

+    const int kTokenBytes = 12;

[Peter Kasting, 2014/05/09 21:35:07]

This should be a size_t

[groby-ooo-7-16, 2014/05/09 22:18:09]

Done.

+    std::string raw_data;
+    base::RandBytes(WriteInto(&raw_data, kTokenBytes + 1), kTokenBytes);
+    base::Base64Encode(raw_data, &current_token_);
+  }
+
+  // Extend expiration time another 60 seconds.
+  token_expiration_time_ = base::Time::Now() + base::TimeDelta::FromSeconds(60);

[Peter Kasting, 2014/05/09 21:35:07]

Fetch the time once atop the function instead of calling Now() repeatedly.

[groby-ooo-7-16, 2014/05/09 22:18:09]

Done.

+
+  return current_token_;
+}