predictors: Collect page load metrics for ResourcePrefetchPredictor.

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
index 2080bf23393b93780edcd8421dee1d1f39f7bc33..b1b1d7fd032d766acc24778316e575682c60a31d 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
@@ -23,6 +23,7 @@
 #include "chrome/browser/page_load_metrics/observers/prerender_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/protocol_page_load_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/page_load_metrics_embedder_interface.h"
 #include "chrome/browser/page_load_metrics/page_load_tracker.h"
@@ -94,6 +95,12 @@ void PageLoadMetricsEmbedder::RegisterObservers(
     tracker->AddObserver(
         base::MakeUnique<AndroidPageLoadMetricsObserver>(web_contents_));
 #endif  // OS_ANDROID
+    std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
+        resource_prefetch_predictor_observer =

[Benoit L, 2017/01/13 17:31:56]

nit: observer is fine as a variable name here :-)

[alexilin, 2017/01/24 12:49:20]

I'm trying to be more consistent with the names around
(no_state_prefetch_observer, prerender_observer). 
This name isn't scoped so it will be confusing to use it along with other
observers.

+            ResourcePrefetchPredictorPageLoadMetricsObserver::CreateIfNeeded(
+                web_contents_);
+    if (resource_prefetch_predictor_observer)
+      tracker->AddObserver(std::move(resource_prefetch_predictor_observer));
   } else {
     std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
         prerender_observer =