Add multi_profile_user_count field to system_profile proto.

chrome/browser/metrics/metrics_log.cc

Index: chrome/browser/metrics/metrics_log.cc
diff --git a/chrome/browser/metrics/metrics_log.cc b/chrome/browser/metrics/metrics_log.cc
index f2962a5015a797296396ea2cb0afa8db2c23b025..64383e0667c0dcc50f7ed4e79ae3bd35edbb4928 100644
--- a/chrome/browser/metrics/metrics_log.cc
+++ b/chrome/browser/metrics/metrics_log.cc
@@ -62,6 +62,10 @@
 extern "C" IMAGE_DOS_HEADER __ImageBase;
 #endif
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/user_manager.h"
+#endif
+
 using content::GpuDataManager;
 using metrics::OmniboxEventProto;
 using metrics::PerfDataProto;
@@ -379,7 +383,14 @@ static base::LazyInstance<std::string>::Leaky
   g_version_extension = LAZY_INSTANCE_INITIALIZER;
 
 MetricsLog::MetricsLog(const std::string& client_id, int session_id)
-    : MetricsLogBase(client_id, session_id, MetricsLog::GetVersionString()) {}
+    : MetricsLogBase(client_id, session_id, MetricsLog::GetVersionString()) {
+#if defined(OS_CHROMEOS)
+  initial_multi_profile_user_count_ = 0;

[Ilya Sherman, 2013/09/30 23:42:52]

nit: Please move this to the initializer list.

+  chromeos::UserManager* user_manager = chromeos::UserManager::Get();
+  if (user_manager && user_manager->IsMultipleProfilesAllowed())
+    initial_multi_profile_user_count_ = user_manager->GetLoggedInUsers().size();
+#endif
+}
 
 MetricsLog::~MetricsLog() {}
 
@@ -799,6 +810,15 @@ void MetricsLog::RecordEnvironmentProto(
                  base::Unretained(this)));
   DCHECK(adapter_.get());
   WriteBluetoothProto(hardware);
+
+  chromeos::UserManager* user_manager = chromeos::UserManager::Get();
+  if (user_manager && user_manager->IsMultipleProfilesAllowed()) {
+    int user_count = user_manager->GetLoggedInUsers().size();
+    // We invalidate the user count if it changed while the log was open.
+    if (user_count != initial_multi_profile_user_count_)
+      user_count = 0;
+    system_profile->set_multi_profile_user_count(user_count);
+  }
 #endif
 }