Add PageLoad.* metrics for Offline Previews

chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc

Index: chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5dd97e91948f6b7d410209997ee739cd2a76d1d4
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc
@@ -0,0 +1,144 @@
+// 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/previews_page_load_metrics_observer.h"
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h"
+#include "chrome/common/page_load_metrics/page_load_timing.h"
+#include "content/public/browser/web_contents.h"
+
+namespace previews {
+
+namespace {
+
+const char kDefaultTestUrl[] = "https://google.com";

[tbansal1, 2016/08/18 22:04:53]

s/kDefaultTestUrl/kDefaultTestUrl1/

[RyanSturm, 2016/08/19 19:10:38]

Done.

+const char kDefaultTestUrl2[] = "https://example.com";
+
+class TestPreviewsPageLoadMetricsObserver
+    : public PreviewsPageLoadMetricsObserver {
+ public:
+  explicit TestPreviewsPageLoadMetricsObserver(bool offline_preview)
+      : offline_preview_(offline_preview) {}
+  ~TestPreviewsPageLoadMetricsObserver() override {}
+
+  // Whether a |web_contents| is an offline pages preview. Overridden in

[tbansal1, 2016/08/18 22:04:53]

No need for comments here. Comments from the base class should suffice.

[RyanSturm, 2016/08/19 19:10:38]

Done.

+  // testing.
+  bool IsOfflinePreview(content::WebContents* web_contents) const override {
+    return offline_preview_;
+  }
+
+ private:
+  bool offline_preview_;
+};
+
+}  // namespace
+
+class PreviewsPageLoadMetricsObserverTest
+    : public page_load_metrics::PageLoadMetricsObserverTestHarness {
+ public:
+  PreviewsPageLoadMetricsObserverTest() : is_offline_preview_(false) {}
+
+  void ResetTest() {
+    // Reset to the default testing state. Does not reset histogram state.
+    timing_.navigation_start = base::Time::FromDoubleT(1);
+    timing_.response_start = base::TimeDelta::FromSeconds(2);
+    timing_.parse_start = base::TimeDelta::FromSeconds(3);
+    timing_.first_contentful_paint = base::TimeDelta::FromSeconds(4);
+    timing_.first_image_paint = base::TimeDelta::FromSeconds(5);
+    timing_.first_text_paint = base::TimeDelta::FromSeconds(6);
+    timing_.load_event_start = base::TimeDelta::FromSeconds(7);
+    PopulateRequiredTimingFields(&timing_);
+  }
+
+  void RunTest(bool is_offline_preview) {
+    is_offline_preview_ = is_offline_preview;
+    NavigateAndCommit(GURL(kDefaultTestUrl));
+    SimulateTimingUpdate(timing_);
+
+    // Navigate again to force OnComplete, which happens when a new navigation
+    // occurs.
+    NavigateAndCommit(GURL(kDefaultTestUrl2));
+  }
+
+  // Verify that, if expected and actual are set, their values are equal.
+  // Otherwise, verify that both are unset.
+  void ExpectEqualOrUnset(const base::Optional<base::TimeDelta>& expected,
+                          const base::Optional<base::TimeDelta>& actual) {
+    if (expected && actual) {
+      EXPECT_EQ(expected.value(), actual.value());
+    } else {
+      EXPECT_TRUE(!expected);
+      EXPECT_TRUE(!actual);
+    }
+  }
+
+  void ValidateHistograms() {
+    ValidateHistogramsForSuffix(
+        internal::kHistogramDOMContentLoadedEventFiredSuffix,
+        timing_.dom_content_loaded_event_start);
+    ValidateHistogramsForSuffix(internal::kHistogramFirstLayoutSuffix,
+                                timing_.first_layout);
+    ValidateHistogramsForSuffix(internal::kHistogramLoadEventFiredSuffix,
+                                timing_.load_event_start);
+    ValidateHistogramsForSuffix(internal::kHistogramFirstContentfulPaintSuffix,
+                                timing_.first_contentful_paint);
+    ValidateHistogramsForSuffix(internal::kHistogramFirstImagePaintSuffix,
+                                timing_.first_image_paint);
+    ValidateHistogramsForSuffix(internal::kHistogramFirstPaintSuffix,
+                                timing_.first_paint);
+    ValidateHistogramsForSuffix(internal::kHistogramFirstTextPaintSuffix,
+                                timing_.first_text_paint);
+    ValidateHistogramsForSuffix(internal::kHistogramParseStartSuffix,
+                                timing_.parse_start);
+  }
+
+  void ValidateHistogramsForSuffix(
+      const std::string& histogram_suffix,
+      const base::Optional<base::TimeDelta>& event) {
+    histogram_tester().ExpectTotalCount(
+        std::string(internal::kHistogramOfflinePreviewsPrefix)
+            .append(histogram_suffix),
+        is_offline_preview_ ? 1 : 0);
+    if (!is_offline_preview_)
+      return;
+    histogram_tester().ExpectUniqueSample(
+        std::string(internal::kHistogramOfflinePreviewsPrefix)
+            .append(histogram_suffix),
+        static_cast<base::HistogramBase::Sample>(
+            event.value().InMilliseconds()),
+        1);
+  }
+
+ protected:
+  void RegisterObservers(page_load_metrics::PageLoadTracker* tracker) override {
+    tracker->AddObserver(base::WrapUnique(
+        new TestPreviewsPageLoadMetricsObserver(is_offline_preview_)));
+  }
+
+  page_load_metrics::PageLoadTiming timing_;

[tbansal1, 2016/08/18 22:04:53]

Why does this need to be protected (and not private)?

[RyanSturm, 2016/08/19 19:10:38]

Done.

+
+ private:
+  bool is_offline_preview_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreviewsPageLoadMetricsObserverTest);
+};
+
+TEST_F(PreviewsPageLoadMetricsObserverTest, NoPreview) {
+  ResetTest();
+  RunTest(false);
+  ValidateHistograms();
+}
+
+TEST_F(PreviewsPageLoadMetricsObserverTest, OfflinePreviews) {
+  ResetTest();
+  RunTest(true);
+  ValidateHistograms();
+}
+
+}  //  namespace previews