Add PageLoad metrics for multi-tab loading cases

chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer_browsertest.cc

Index: chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer_browsertest.cc
diff --git a/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer_browsertest.cc b/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer_browsertest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..eab2896b1e133b0b1815ef8e958af178194558d6
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer_browsertest.cc
@@ -0,0 +1,94 @@
+// Copyright 2017 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/multi_tab_loading_page_load_metrics_observer.h"
+
+#include "base/test/histogram_tester.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/ui_test_utils.h"
+#include "content/public/test/browser_test.h"
+#include "content/public/test/browser_test_utils.h"
+#include "net/test/embedded_test_server/embedded_test_server.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class MultiTabLoadingPageLoadMetricsBrowserTest : public InProcessBrowserTest {
+ public:
+  MultiTabLoadingPageLoadMetricsBrowserTest() {}
+  ~MultiTabLoadingPageLoadMetricsBrowserTest() override {}
+
+ protected:
+  GURL GetTestURL() { return embedded_test_server()->GetURL("/simple.html"); }
+
+  void NavigateToURLWithoutWaiting(GURL url) {
+    ui_test_utils::NavigateToURLWithDisposition(
+        browser(), url, WindowOpenDisposition::CURRENT_TAB,
+        ui_test_utils::BROWSER_TEST_NONE);
+  }
+
+  void SetUpOnMainThread() override {
+    ASSERT_TRUE(embedded_test_server()->Start());
+    InProcessBrowserTest::SetUpOnMainThread();
+  }
+};
+
+IN_PROC_BROWSER_TEST_F(MultiTabLoadingPageLoadMetricsBrowserTest, SingleTab) {
+  base::HistogramTester histogram_tester;
+
+  ui_test_utils::NavigateToURL(browser(), GetTestURL());
+
+  // Navigate away to force the histogram recording.
+  ui_test_utils::NavigateToURL(browser(), GURL(url::kAboutBlankURL));
+
+  histogram_tester.ExpectTotalCount(internal::kHistogramMultiTabLoadingLoad, 0);
+  histogram_tester.ExpectTotalCount(
+      internal::kBackgroundHistogramMultiTabLoadingLoad, 0);
+}
+
+IN_PROC_BROWSER_TEST_F(MultiTabLoadingPageLoadMetricsBrowserTest,
+                       MultiTabForeground) {
+  base::HistogramTester histogram_tester;
+
+  NavigateToURLWithoutWaiting(embedded_test_server()->GetURL("/hung"));
+
+  // Open a new foreground tab.
+  ui_test_utils::NavigateToURLWithDispositionBlockUntilNavigationsComplete(
+      browser(), GetTestURL(), 1, WindowOpenDisposition::NEW_FOREGROUND_TAB,
+      ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
+
+  // Navigate away to force the histogram recording.
+  ui_test_utils::NavigateToURL(browser(), GURL(url::kAboutBlankURL));
+
+  histogram_tester.ExpectTotalCount(internal::kHistogramMultiTabLoadingLoad, 1);
+  histogram_tester.ExpectTotalCount(
+      internal::kBackgroundHistogramMultiTabLoadingLoad, 0);
+}
+
+IN_PROC_BROWSER_TEST_F(MultiTabLoadingPageLoadMetricsBrowserTest,
+                       MultiTabBackground) {
+  base::HistogramTester histogram_tester;
+
+  NavigateToURLWithoutWaiting(embedded_test_server()->GetURL("/hung"));
+
+  // Open a tab in the background.
+  ui_test_utils::NavigateToURLWithDispositionBlockUntilNavigationsComplete(
+      browser(), GetTestURL(), 1, WindowOpenDisposition::NEW_BACKGROUND_TAB,
+      ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
+
+  // Close the foreground tab.
+  TabStripModel* tab_strip_model = browser()->tab_strip_model();
+  content::WebContentsDestroyedWatcher destroyed_watcher(
+      tab_strip_model->GetWebContentsAt(0));
+  EXPECT_TRUE(tab_strip_model->CloseWebContentsAt(0, 0));
+  destroyed_watcher.Wait();
+  // Now the background tab should have moved to the foreground.
+
+  // Navigate away to force the histogram recording.
+  ui_test_utils::NavigateToURL(browser(), GURL(url::kAboutBlankURL));
+
+  histogram_tester.ExpectTotalCount(internal::kHistogramMultiTabLoadingLoad, 0);
+  histogram_tester.ExpectTotalCount(
+      internal::kBackgroundHistogramMultiTabLoadingLoad, 1);
+}