Remove Extensions.NetworkDelayStartup histogram

extensions/browser/api/web_request/web_request_api.cc

 // Copyright (c) 2012 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 "extensions/browser/api/web_request/web_request_api.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 1596 matching lines @@
 
     activity_monitor::OnWebRequestApiUsed(
         static_cast<content::BrowserContext*>(browser_context), extension_id,
         blocked_request.request->url(), blocked_request.is_incognito,
         event_name, SummarizeResponseDelta(event_name, *delta));
 
     blocked_request.response_deltas.push_back(
         linked_ptr<helpers::EventResponseDelta>(delta));
   }
 
-  base::TimeDelta block_time =
-      base::Time::Now() - blocked_request.blocking_time;
   if (!extension_id.empty()) {
+    base::TimeDelta block_time =
+        base::Time::Now() - blocked_request.blocking_time;
     request_time_tracker_->IncrementExtensionBlockTime(
         extension_id, request_id, block_time);
-  } else {
-    // |extension_id| is empty for requests blocked on startup waiting for the
-    // declarative rules to be read from disk.
-    UMA_HISTOGRAM_TIMES("Extensions.NetworkDelayStartup", block_time);
   }
 
   if (num_handlers_blocking == 0) {
     blocked_request.request->LogUnblocked();
     ExecuteDeltas(browser_context, request_id, true);
   } else {
     // Update the URLRequest to make sure it's tagged with an extension that's
     // still blocking it.  This may end up being the same extension as before.
     Listeners& listeners = listeners_[browser_context][event_name];
 
@@ skipping 630 matching lines @@
   // Since EventListeners are segmented by browser_context, check that
   // last, as it is exceedingly unlikely to be different.
   return extension_id == that.extension_id &&
          sub_event_name == that.sub_event_name &&
          web_view_instance_id == that.web_view_instance_id &&
          embedder_process_id == that.embedder_process_id &&
          browser_context == that.browser_context;
 }
 
 }  // namespace extensions