[NoStatePrefetch] Add performance histograms.

chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc b/chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc
index f766b71b7986b4fafaaa3df9660b378f5d7e2943..180fb2685100640ca50301038437d86d21832216 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc
@@ -4,10 +4,14 @@
 
 #include "base/macros.h"
 #include "base/test/histogram_tester.h"
+#include "base/time/time.h"
 #include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 #include "chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/no_state_prefetch_page_load_metrics_observer.h"
+#include "chrome/browser/prerender/prerender_histograms.h"
+#include "chrome/browser/prerender/prerender_origin.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_navigator_params.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ -427,3 +431,31 @@ IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,
   histogram_tester_.ExpectTotalCount(
       internal::kHistogramParseStartToFirstMeaningfulPaint, 0);
 }
+
+IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,

[Bryan McQuade, 2016/09/19 16:35:02]

i just landed a change that renamed these tests to PageLoadMetricsBrowserTest -
you'll need to rebase and then rename your tests to match, thanks!

+                       NoStatePrefetchObserverCacheable) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+
+  ui_test_utils::NavigateToURL(browser(),
+                               embedded_test_server()->GetURL("/title1.html"));
+  NavigateToUntrackedUrl();
+
+  histogram_tester_.ExpectTotalCount(

[Bryan McQuade, 2016/09/19 16:35:02]

for completeness, can we also verify that the count for the no-store variant is
zero here?

+      prerender::PrerenderHistograms::GetFirstContentfulPaintHistogrameName(
+          prerender::ORIGIN_NONE, false, false, base::TimeDelta()),
+      1);
+}
+
+IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,
+                       NoStatePrefetchObserverNoStore) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+
+  ui_test_utils::NavigateToURL(browser(),
+                               embedded_test_server()->GetURL("/nostore.html"));
+  NavigateToUntrackedUrl();
+
+  histogram_tester_.ExpectTotalCount(

[Bryan McQuade, 2016/09/19 16:35:02]

likewise, let's verify that the non-no-store variant has a count of zero here.

+      prerender::PrerenderHistograms::GetFirstContentfulPaintHistogrameName(
+          prerender::ORIGIN_NONE, false, true, base::TimeDelta()),
+      1);
+}