Add histogram to track prerender sessions

chrome/browser/browser_main.cc

 // Copyright (c) 2011 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/browser_main.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 38 matching lines @@
 #include "chrome/browser/net/chrome_dns_cert_provenance_checker.h"
 #include "chrome/browser/net/chrome_dns_cert_provenance_checker_factory.h"
 #include "chrome/browser/net/metadata_url_request.h"
 #include "chrome/browser/net/predictor_api.h"
 #include "chrome/browser/net/sdch_dictionary_fetcher.h"
 #include "chrome/browser/net/websocket_experiment/websocket_experiment_runner.h"
 #include "chrome/browser/plugin_service.h"
 #include "chrome/browser/prefs/browser_prefs.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/prefs/pref_value_store.h"
+#include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/printing/cloud_print/cloud_print_proxy_service.h"
 #include "chrome/browser/printing/print_dialog_cloud.h"
 #include "chrome/browser/process_singleton.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/renderer_host/resource_dispatcher_host.h"
 #include "chrome/browser/search_engines/search_engine_type.h"
 #include "chrome/browser/search_engines/template_url.h"
 #include "chrome/browser/search_engines/template_url_model.h"
 #include "chrome/browser/service/service_process_control.h"
@@ skipping 148 matching lines @@
   PostEarlyInitialization();
 }
 
 // This will be called after the command-line has been mutated by about:flags
 void BrowserMainParts::SetupFieldTrials() {
   // Note: make sure to call ConnectionFieldTrial() before
   // ProxyConnectionsFieldTrial().
   ConnectionFieldTrial();
   SocketTimeoutFieldTrial();
   ProxyConnectionsFieldTrial();
-  PrefetchFieldTrial();
+  PrefetchAndPrerenderFieldTrial();
   SpdyFieldTrial();
   ConnectBackupJobsFieldTrial();
 }
 
 // This is an A/B test for the maximum number of persistent connections per
 // host. Currently Chrome, Firefox, and IE8 have this value set at 6. Safari
 // uses 4, and Fasterfox (a plugin for Firefox that supposedly configures it to
 // run faster) uses 8. We would like to see how much of an effect this value has
 // on browsing. Too large a value might cause us to run into SYN flood detection
 // mechanisms.
@@ skipping 184 matching lines @@
         &value);
     if (value > 0)
       net::SpdySession::set_max_concurrent_streams(value);
   }
 }
 
 // If any of --enable-prerender, --enable-content-prefetch or
 // --disable-content-prefetch are set, use those to determine if
 // prefetch is enabled. Otherwise, randomly assign users to an A/B test for
 // prefetching.
-void BrowserMainParts::PrefetchFieldTrial() {
+void BrowserMainParts::PrefetchAndPrerenderFieldTrial() {
   if (parsed_command_line().HasSwitch(switches::kEnableContentPrefetch) ||
       parsed_command_line().HasSwitch(switches::kEnablePagePrerender))
     ResourceDispatcherHost::set_is_prefetch_enabled(true);
   else if (parsed_command_line().HasSwitch(switches::kDisableContentPrefetch)) {
     ResourceDispatcherHost::set_is_prefetch_enabled(false);
   } else {
     const base::FieldTrial::Probability kPrefetchDivisor = 1000;
     const base::FieldTrial::Probability no_prefetch_probability = 500;
     // After June 30, 2011 builds, it will always be in default group.
     scoped_refptr<base::FieldTrial> trial(
         new base::FieldTrial("Prefetch", kPrefetchDivisor,
             "ContentPrefetchEnabled", 2011, 6, 30));
     const int yes_prefetch_grp = trial->kDefaultGroupNumber;
     trial->AppendGroup("ContentPrefetchDisabled", no_prefetch_probability);
     const int trial_grp = trial->group();
     ResourceDispatcherHost::set_is_prefetch_enabled(
         trial_grp == yes_prefetch_grp);
   }
+
+  PrerenderManager::PrerenderManagerMode prerender_mode;

[cbentzel, 2011/01/27 04:38:34]

Uninitialized values always scare me. Maybe change if/else to ternary, or
initialize to DISABLED. 

[gavinp, 2011/01/27 05:25:26]

Done.

+  if (parsed_command_line().HasSwitch(switches::kEnablePagePrerender))
+    prerender_mode = PrerenderManager::PRERENDER_MODE_ENABLED;
+  else
+    prerender_mode = PrerenderManager::PRERENDER_MODE_DISABLED;
+  PrerenderManager::SetMode(prerender_mode);
+
+  UMA_HISTOGRAM_ENUMERATION("Prerender.Sessions", prerender_mode,

[cbentzel, 2011/01/27 04:38:34]

Do we have other Prerender-prefixed histograms at this point, or is this the
first one?

[gavinp, 2011/01/27 05:25:26]

This is the first one.  I couldn't think of another group to put it in reviewing
them: ultimately I guess our histograms will be split between PLT and Prerender?

+                            PrerenderManager::PRERENDER_MODE_MAX);
 }
 
 // If neither --enable-connect-backup-jobs or --disable-connect-backup-jobs is
 // specified, run an A/B test for automatically establishing backup TCP
 // connections when a certain timeout value is exceeded.
 void BrowserMainParts::ConnectBackupJobsFieldTrial() {
   if (parsed_command_line().HasSwitch(switches::kEnableConnectBackupJobs)) {
     net::internal::ClientSocketPoolBaseHelper::set_connect_backup_jobs_enabled(
         true);
   } else if (parsed_command_line().HasSwitch(
@@ skipping 1324 matching lines @@
 #if defined(OS_CHROMEOS)
   // To be precise, logout (browser shutdown) is not yet done, but the
   // remaining work is negligible, hence we say LogoutDone here.
   chromeos::BootTimesLoader::Get()->AddLogoutTimeMarker("LogoutDone",
                                                         false);
   chromeos::BootTimesLoader::Get()->WriteLogoutTimes();
 #endif
   TRACE_EVENT_END("BrowserMain", 0, 0);
   return result_code;
 }