Create LoadingDataCollector class and have observers rely on it instead of ResourcePrefetchPredictor

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

 // Copyright 2015 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/page_load_metrics_initialize.h"
 
+#include <memory>
+#include <utility>
+
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 #if defined(OS_ANDROID)
 #include "chrome/browser/page_load_metrics/observers/android_page_load_metrics_observer.h"
 #endif  // OS_ANDROID
 #include "chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h"
@@ skipping 97 matching lines @@
         no_state_prefetch_observer =
             NoStatePrefetchPageLoadMetricsObserver::CreateIfNeeded(
                 web_contents_);
     if (no_state_prefetch_observer)
       tracker->AddObserver(std::move(no_state_prefetch_observer));
 #if defined(OS_ANDROID)
     tracker->AddObserver(
         base::MakeUnique<AndroidPageLoadMetricsObserver>(web_contents_));
 #endif  // OS_ANDROID
     std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
-        resource_prefetch_predictor_observer =
+        loading_predictor_observer =
             ResourcePrefetchPredictorPageLoadMetricsObserver::CreateIfNeeded(

[alexilin, 2017/06/07 12:37:31]

nit:
We could rename ResourcePrefetchPredictorPageLoadMetricsObserver class to
LoadingPredictorPageLoadMetricsObserver as well.

[trevordixon, 2017/06/07 13:17:55]

OK, done.

                 web_contents_);
-    if (resource_prefetch_predictor_observer)
-      tracker->AddObserver(std::move(resource_prefetch_predictor_observer));
+    if (loading_predictor_observer)
+      tracker->AddObserver(std::move(loading_predictor_observer));
   } else {
     std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
         prerender_observer =
             PrerenderPageLoadMetricsObserver::CreateIfNeeded(web_contents_);
     if (prerender_observer)
       tracker->AddObserver(std::move(prerender_observer));
   }
   tracker->AddObserver(
       base::MakeUnique<OmniboxSuggestionUsedMetricsObserver>(IsPrerendering()));
   tracker->AddObserver(
@@ skipping 21 matching lines @@
 
 void InitializePageLoadMetricsForWebContents(
     content::WebContents* web_contents,
     const base::Optional<content::WebContents::CreateParams>& create_params) {
   page_load_metrics::MetricsWebContentsObserver::CreateForWebContents(
       web_contents, create_params,
       base::MakeUnique<PageLoadMetricsEmbedder>(web_contents));
 }
 
 }  // namespace chrome