Refactor PageLoadMetricsObserver completion callback policy

chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.cc

 // Copyright 2016 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 "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
 #include "components/page_load_metrics/browser/page_load_metrics_util.h"
 #include "third_party/WebKit/public/platform/WebLoadingBehaviorFlag.h"
 
 namespace internal {
 const char kHistogramDocWriteFirstContentfulPaint[] =
@@ skipping 157 matching lines @@
         !(info.metadata.behavior_flags &
           blink::WebLoadingBehaviorFlag::WebLoadingBehaviorDocumentWriteBlock));
     UMA_HISTOGRAM_COUNTS(internal::kHistogramDocWriteBlockReloadCount, 1);
     doc_write_block_reload_observed_ = true;
   }
 }
 
 void DocumentWritePageLoadMetricsObserver::OnComplete(
     const page_load_metrics::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {
-  if (!info.time_to_commit || timing.IsEmpty())

[Charlie Harrison, 2016/07/18 20:02:18]

Why remove the IsEmpty() check?

[Bryan McQuade, 2016/07/19 12:55:38]

Yeah, you're right, we might as well return early here if timing is empty. Done.

-    return;
   if (info.metadata.behavior_flags &
       blink::WebLoadingBehaviorFlag::WebLoadingBehaviorDocumentWriteEvaluator) {
     LogDocumentWriteEvaluatorData(timing, info);
   }
   if (info.metadata.behavior_flags &
       blink::WebLoadingBehaviorFlag::WebLoadingBehaviorDocumentWriteBlock) {
     LogDocumentWriteBlockData(timing, info);
   }
 }
 
@@ skipping 222 matching lines @@
     PAGE_LOAD_HISTOGRAM(
         internal::kBackgroundHistogramDocWriteBlockParseBlockedOnScriptComplete,
         timing.parse_blocked_on_script_load_duration.value());
     PAGE_LOAD_HISTOGRAM(
         internal::
             kBackgroundDocWriteBlockParseBlockedOnScriptLoadDocWriteComplete,
         timing.parse_blocked_on_script_load_from_document_write_duration
             .value());
   }
 }