Automatically adapt to faster/slower uploads of renderer histograms...

chrome/browser/browser_main.cc

 // Copyright (c) 2006-2009 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 "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <commctrl.h>
 #endif
@@ skipping 28 matching lines @@
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/net/dns_global.h"
 #include "chrome/browser/plugin_service.h"
 #include "chrome/browser/process_singleton.h"
 #include "chrome/browser/profile_manager.h"
 #include "chrome/browser/shell_integration.h"
 #include "chrome/browser/user_data_manager.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/histogram_synchronizer.h"
 #include "chrome/common/jstemplate_builder.h"
 #include "chrome/common/main_function_params.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/pref_service.h"
 #include "chrome/common/result_codes.h"
 #include "grit/chromium_strings.h"
 #include "grit/generated_resources.h"
 #include "grit/net_resources.h"
 #include "net/base/cookie_monster.h"
 #include "net/base/net_module.h"
@@ skipping 372 matching lines @@
 
   if (parsed_command_line.HasSwitch(switches::kEnableFileCookies)) {
     // Enable cookie storage for file:// URLs.  Must do this before the first
     // Profile (and therefore the first CookieMonster) is created.
     net::CookieMonster::EnableFileScheme();
   }
 
   // Initialize histogram statistics gathering system.
   StatisticsRecorder statistics;
 
+  // Initialize histogram synchronizer system. This is a singleton and is used
+  // for posting tasks via NewRunnableMethod. Its deleted when it goes out of
+  // scope. Even though NewRunnableMethod does AddRef and Release, the object
+  // will not be deleted after the Task is executed.
+  scoped_refptr<HistogramSynchronizer> histogram_synchronizer =
+      new HistogramSynchronizer();
+
   // Initialize the shared instance of user data manager.
   scoped_ptr<UserDataManager> user_data_manager(UserDataManager::Create());
 
   // Try to create/load the profile.
   ProfileManager* profile_manager = browser_process->profile_manager();
   Profile* profile = profile_manager->GetDefaultProfile(user_data_dir);
   if (!profile) {
     // Ideally, we should be able to run w/o access to disk.  For now, we
     // prompt the user to pick a different user-data-dir and restart chrome
     // with the new dir.
@@ skipping 118 matching lines @@
   PrepareRestartOnCrashEnviroment(parsed_command_line);
 
 #if defined(OS_WIN)
   // Initialize Winsock.
   net::EnsureWinsockInit();
 #endif  // defined(OS_WIN)
 
   // Set up a field trial to see what disabling DNS pre-resolution does to
   // latency of network transactions.
   FieldTrial::Probability kDIVISOR = 100;
-  FieldTrial::Probability k_PROBABILITY_PER_GROUP = 10;  // 10%.
+  FieldTrial::Probability k_PROBABILITY_PER_GROUP = 10;  // 10% probability.
+  // For options we don't (currently) wish to test, we use zero probability.
+  FieldTrial::Probability k_PROBABILITY_DISABLED = 0;
   scoped_refptr<FieldTrial> dns_trial = new FieldTrial("DnsImpact", kDIVISOR);
 
   dns_trial->AppendGroup("_disabled_prefetch", k_PROBABILITY_PER_GROUP);
+  // Don't discard names (erase these lines) yet, as we may use them, and we
+  // have histogram data named for these options.
   int disabled_plus_4_connections = dns_trial->AppendGroup(
-      "_disabled_prefetch_4_connections", k_PROBABILITY_PER_GROUP);
+      "_disabled_prefetch_4_connections", k_PROBABILITY_DISABLED);
   int enabled_plus_4_connections = dns_trial->AppendGroup(
-      "_enabled_prefetch_4_connections", k_PROBABILITY_PER_GROUP);
+      "_enabled_prefetch_4_connections", k_PROBABILITY_DISABLED);
 
   scoped_ptr<chrome_browser_net::DnsPrefetcherInit> dns_prefetch_init;
   if (dns_trial->group() == FieldTrial::kNotParticipating ||
       dns_trial->group() == enabled_plus_4_connections) {
     // Initialize the DNS prefetch system
     dns_prefetch_init.reset(
         new chrome_browser_net::DnsPrefetcherInit(user_prefs));
     chrome_browser_net::DnsPrefetchHostNamesAtStartup(user_prefs, local_state);
     chrome_browser_net::RestoreSubresourceReferrers(local_state);
   }
@@ skipping 139 matching lines @@
   if (metrics)
     metrics->Stop();
 
   // browser_shutdown takes care of deleting browser_process, so we need to
   // release it.
   browser_process.release();
   browser_shutdown::Shutdown();
 
   return result_code;
 }