[AiS] Provide Answers queries with a session token.

chrome/browser/autocomplete/search_provider.cc

Index: chrome/browser/autocomplete/search_provider.cc
diff --git a/chrome/browser/autocomplete/search_provider.cc b/chrome/browser/autocomplete/search_provider.cc
index a08ea8715c87771439b385f14ec7c2024e71dabb..d6979a84f22ccc118ebf23cbd2104ee1af271486 100644
--- a/chrome/browser/autocomplete/search_provider.cc
+++ b/chrome/browser/autocomplete/search_provider.cc
@@ -7,13 +7,16 @@
 #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"
@@ -34,6 +37,7 @@
 #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"
@@ -637,6 +641,11 @@ net::URLFetcher* SearchProvider::CreateSuggestFetcher(
   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)
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableAnswersInSuggest))
+    search_term_args.session_token = GetSessionToken();
+#endif
   GURL suggest_url(template_url->suggestions_url_ref().ReplaceSearchTerms(
       search_term_args));
   if (!suggest_url.is_valid())
@@ -1131,3 +1140,19 @@ void SearchProvider::UpdateDone() {
   // pending, and we're not waiting on Instant.
   done_ = !timer_.IsRunning() && (suggest_results_pending_ == 0);
 }
+
+std::string SearchProvider::GetSessionToken() {
+  base::TimeTicks current_time(base::TimeTicks::Now());
+  // Renew token if it expired.
+  if (current_time > token_expiration_time_) {
+    const size_t kTokenBytes = 12;
+    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_ = current_time + base::TimeDelta::FromSeconds(60);
+
+  return current_token_;
+}