[NoStatePrefetch] Add performance histograms.

chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..13755db2719b4a6cfc571d3ad53f7a93418eb2fe
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.cc
@@ -0,0 +1,63 @@
+// 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/no_state_prefetch_page_load_metrics_observer.h"
+
+#include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+#include "chrome/browser/prerender/prerender_manager_factory.h"
+#include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/web_contents.h"
+#include "net/http/http_response_headers.h"
+
+// static
+void NoStatePrefetchPageLoadMetricsObserver::AddObserverIfNeeded(
+    page_load_metrics::PageLoadTracker* tracker,
+    content::WebContents* web_contents) {
+  prerender::PrerenderManager* manager =
+      prerender::PrerenderManagerFactory::GetForBrowserContext(
+          web_contents->GetBrowserContext());
+  if (!manager)
+    return;
+  tracker->AddObserver(
+      base::MakeUnique<NoStatePrefetchPageLoadMetricsObserver>(manager));
+}
+
+NoStatePrefetchPageLoadMetricsObserver::NoStatePrefetchPageLoadMetricsObserver(
+    prerender::PrerenderManager* manager)
+    : is_no_store_(false),
+      navigation_committed_(false),
+      prerender_manager_(manager) {
+  DCHECK(prerender_manager_);
+}
+
+NoStatePrefetchPageLoadMetricsObserver::
+    ~NoStatePrefetchPageLoadMetricsObserver() {}
+
+void NoStatePrefetchPageLoadMetricsObserver::OnStart(
+    content::NavigationHandle* navigation_handle,
+    const GURL& currently_committed_url,
+    bool started_in_foreground) {
+  start_url_ = navigation_handle->GetURL();
+}
+
+void NoStatePrefetchPageLoadMetricsObserver::OnCommit(
+    content::NavigationHandle* navigation_handle) {
+  navigation_committed_ = true;
+
+  const net::HttpResponseHeaders* response_headers =
+      navigation_handle->GetResponseHeaders();
+
+  is_no_store_ = response_headers &&
+                 response_headers->HasHeaderValue("cache-control", "no-store");
+}
+
+void NoStatePrefetchPageLoadMetricsObserver::OnFirstContentfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  DCHECK(navigation_committed_);

[mmenke, 2016/09/15 17:20:44]

include base/logging.h

+  DCHECK(timing.first_contentful_paint.has_value());
+  prerender_manager_->RecordFirstContentfulPaint(
+      start_url_, is_no_store_, *timing.first_contentful_paint);
+}