When we upgrade, discard all uploadable stats, including old logs...

chrome/browser/metrics/metrics_service.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.
 
 
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
@@ skipping 354 matching lines @@
   local_state->SetInteger(prefs::kStabilityPageLoadCount, 0);
   local_state->SetInteger(prefs::kStabilityRendererCrashCount, 0);
   local_state->SetInteger(prefs::kStabilityRendererHangCount, 0);
 
   local_state->SetInteger(prefs::kSecurityRendererOnSboxDesktop, 0);
   local_state->SetInteger(prefs::kSecurityRendererOnDefaultDesktop, 0);
 
   local_state->SetString(prefs::kStabilityUptimeSec, L"0");
 
   local_state->ClearPref(prefs::kStabilityPluginStats);
+
+  ListValue* unsent_initial_logs = local_state->GetMutableList(
+      prefs::kMetricsInitialLogs);
+  unsent_initial_logs->Clear();
+
+  ListValue* unsent_ongoing_logs = local_state->GetMutableList(
+      prefs::kMetricsOngoingLogs);

[Evan Martin, 2009/06/19 05:14:22]

Can these ever be NULL?  Just want you to be sure.

[jar (doing other things), 2009/06/19 06:07:22]

It is guaranteed to be non-NULL so long as the pref is registered.  It will
create a dictionary if one does not exist, or return the existing dictionary.

All prefs are registered in a local function MetricsService::RegisterPrefs()
which is one of many module initialization functions called from
RegisterAllPrefs() in browser_prefs.cc.   Bottom line: The prefs are registered
whether metrics services are used or not, and hence this return value is always
non-NULL.

+  unsent_ongoing_logs->Clear();
 }
 
 MetricsService::MetricsService()
     : recording_active_(false),
       reporting_active_(false),
       user_permits_upload_(false),
       server_permits_upload_(true),
       state_(INITIALIZED),
       pending_log_(NULL),
       pending_log_text_(""),
@@ skipping 1512 matching lines @@
       L"." + key;
   prof_prefs->SetInteger(pref_key.c_str(), value);
 }
 
 static bool IsSingleThreaded() {
   static PlatformThreadId thread_id = 0;
   if (!thread_id)
     thread_id = PlatformThread::CurrentId();
   return PlatformThread::CurrentId() == thread_id;
 }