Remove URLBlacklistManager.ConstructorBuildTime.

It served its purpose and is now safe to remove.

BUG=827173
R=pastarmovj@chromium.org,isherman@chromium.org

Change-Id: I297865c08486ace46c5a42df698cf169ab5d7f9a
Reviewed-on: https://chromium-review.googlesource.com/1203372
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588507}

components/policy/core/browser/url_blacklist_manager.cc

@@ -17,7 +17,6 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
-#include "base/metrics/histogram_macros.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
@@ -449,7 +448,6 @@ URLBlacklistManager::URLBlacklistManager(PrefService* pref_service)
   // startup.
   if (pref_service_->HasPrefPath(policy_prefs::kUrlBlacklist) ||
       pref_service_->HasPrefPath(policy_prefs::kUrlWhitelist)) {
-    SCOPED_UMA_HISTOGRAM_TIMER("URLBlacklistManager.ConstructorBuildTime");
     SetBlacklist(
         BuildBlacklist(pref_service_->GetList(policy_prefs::kUrlBlacklist),
                        pref_service_->GetList(policy_prefs::kUrlWhitelist)));

tools/metrics/histograms/histograms.xml

@@ -109816,6 +109816,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="URLBlacklistManager.ConstructorBuildTime" units="ms">
+  <obsolete>
+    Served its purpose; deprecated 9/2018 in M71 (https://crbug.com/827173).
+  </obsolete>
   <owner>grt@chromium.org</owner>
   <summary>
     The time it took to build and set the URL blacklist on the main thread