Remove obsolete Installer.* metrics.

These metrics were replaced by the UpdateEngine.* metrics.

Bug: chromium:355745
Test: FEATURES=test emerge-link update_engine

Change-Id: I80d0db44681c428898500dd9099918e98ae40b28
diff --git a/omaha_request_action.cc b/omaha_request_action.cc
index 05d950f..8967762 100644
--- a/omaha_request_action.cc
+++ b/omaha_request_action.cc
@@ -1343,13 +1343,7 @@
   if (!prefs->SetInt64(kPrefsInstallDateDays, install_date_days))
     return false;
 
-  string metric_name = "Installer.InstallDateProvisioningSource";
-  system_state->metrics_lib()->SendEnumToUMA(
-      metric_name,
-      static_cast<int>(source),  // Sample.
-      kProvisionedMax);          // Maximum.
-
-  metric_name = metrics::kMetricInstallDateProvisioningSource;
+  string metric_name = metrics::kMetricInstallDateProvisioningSource;
   system_state->metrics_lib()->SendEnumToUMA(
       metric_name,
       static_cast<int>(source),  // Sample.