Add UKM for full viewport image LCP

Privacy review:
https://docs.google.com/document/d/1L93H6TYrtq4qRWzvEa3H7uKZhwWCtTTJ_bT6QFdg_ys/edit#heading=h.k5jx6iluw4yt

Bug: 1133883
Change-Id: I07a89ebca144e8ee7d5600f2b5eba79b7069a64c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2450610
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816645}

third_party/blink/renderer/core/paint/image_paint_timing_detector.cc

@@ -3,6 +3,8 @@
 // found in the LICENSE file.
 #include "third_party/blink/renderer/core/paint/image_paint_timing_detector.h"
 
+#include "services/metrics/public/cpp/ukm_builders.h"
+#include "services/metrics/public/cpp/ukm_recorder.h"
 #include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/frame/local_frame_view.h"
 #include "third_party/blink/renderer/core/layout/layout_image_resource.h"
@@ -175,6 +177,17 @@ void ImagePaintTimingDetector::NotifyImageRemoved(
   need_update_timing_at_frame_end_ = true;
 }
 
+void ImagePaintTimingDetector::StopRecordEntries() {
+  is_recording_ = false;
+  if (frame_view_->GetFrame().IsMainFrame()) {
+    DCHECK(frame_view_->GetFrame().GetDocument());
+    ukm::builders::Blink_PaintTiming(
+        frame_view_->GetFrame().GetDocument()->UkmSourceID())
+        .SetLCPDebugging_HasViewportImage(contains_full_viewport_image_)
+        .Record(ukm::UkmRecorder::Get());
+  }
+}
+
 void ImagePaintTimingDetector::RegisterNotifySwapTime() {
   auto callback = WTF::Bind(&ImagePaintTimingDetector::ReportSwapTime,
                             WrapCrossThreadWeakPersistent(this),
@@ -307,8 +320,10 @@ uint64_t ImagePaintTimingDetector::ComputeImageRectSize(
   // SVG, so |rect_size| can be larger than |*viewport_size| in edge cases. If
   // the rect occupies the whole viewport, disregard this candidate by saying
   // the size is 0.
-  if (rect_size >= *viewport_size_)
+  if (rect_size >= *viewport_size_) {
+    contains_full_viewport_image_ = true;
     return 0;
+  }
 
   rect_size = DownScaleIfIntrinsicSizeIsSmaller(
       rect_size, intrinsic_size.Area(),

third_party/blink/renderer/core/paint/image_paint_timing_detector.h

@@ -266,7 +266,7 @@ class CORE_EXPORT ImagePaintTimingDetector final
   // an image is recorded before stopping recording, and finish loading after
   // stopping recording, the detector can still observe the loading being
   // finished.
-  inline void StopRecordEntries() { is_recording_ = false; }
+  void StopRecordEntries();
   inline bool IsRecording() const { return is_recording_; }
   inline bool FinishedReportingImages() const {
     return !is_recording_ && num_pending_swap_callbacks_ == 0;
@@ -322,6 +322,8 @@ class CORE_EXPORT ImagePaintTimingDetector final
   // |FindLargestPaintCandidate| occur during the paint tree walk.
   bool need_update_timing_at_frame_end_ = false;
 
+  bool contains_full_viewport_image_ = false;
+
   // We cache the viewport size computation to avoid performing it on every
   // image. This value is reset when paint is finished and is computed if unset
   // when needed. 0 means that the size has not been computed.

third_party/blink/renderer/core/paint/image_paint_timing_detector_test.cc

@@ -8,6 +8,8 @@
 #include "base/test/test_mock_time_task_runner.h"
 #include "base/test/trace_event_analyzer.h"
 #include "build/build_config.h"
+#include "components/ukm/test_ukm_recorder.h"
+#include "services/metrics/public/cpp/ukm_builders.h"
 #include "third_party/blink/public/web/web_performance.h"
 #include "third_party/blink/public/web/web_widget_client.h"
 #include "third_party/blink/renderer/core/frame/frame_test_helpers.h"
@@ -50,6 +52,8 @@ namespace blink {
   "oIRn/wsGUQIIy4Vr9TH6SYFCNzw4nALn5627K4vIttOUOwfa5YnrDYzt/9OLv9I5l8kk5hZ3XL" \
   "O20b7tbR7zHLy/BX8G0IeBEM7ZN1NGIaFUaKLgAAAAAElFTkSuQmCC"
 
+using UkmPaintTiming = ukm::builders::Blink_PaintTiming;
+
 class ImagePaintTimingDetectorTest : public testing::Test,
                                      public PaintTestConfigurations {
  public:
@@ -259,6 +263,10 @@ class ImagePaintTimingDetectorTest : public testing::Test,
     GetPaintTimingDetector().NotifyScroll(mojom::blink::ScrollType::kUser);
   }
 
+  void SimulateKeyDown() {
+    GetPaintTimingDetector().NotifyInputEvent(WebInputEvent::Type::kKeyDown);
+  }
+
   void SimulateKeyUp() {
     GetPaintTimingDetector().NotifyInputEvent(WebInputEvent::Type::kKeyUp);
   }
@@ -305,6 +313,7 @@ TEST_P(ImagePaintTimingDetectorTest, LargestImagePaint_NoImage) {
 }
 
 TEST_P(ImagePaintTimingDetectorTest, LargestImagePaint_OneImage) {
+  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
   SetBodyInnerHTML(R"HTML(
     <img id="target"></img>
   )HTML");
@@ -315,6 +324,13 @@ TEST_P(ImagePaintTimingDetectorTest, LargestImagePaint_OneImage) {
   EXPECT_EQ(record->first_size, 25ul);
   EXPECT_TRUE(record->loaded);
   EXPECT_EQ(ExperimentalLargestPaintSize(), 25ul);
+  // Simulate some input event to force StopRecordEntries().
+  SimulateKeyDown();
+  auto entries = test_ukm_recorder.GetEntriesByName(UkmPaintTiming::kEntryName);
+  EXPECT_EQ(1ul, entries.size());
+  auto* entry = entries[0];
+  test_ukm_recorder.ExpectEntryMetric(
+      entry, UkmPaintTiming::kLCPDebugging_HasViewportImageName, false);
 }
 
 TEST_P(ImagePaintTimingDetectorTest, InsertionOrderIsSecondaryRankingKey) {
@@ -1234,4 +1250,23 @@ TEST_P(ImagePaintTimingDetectorTest, OpacityZeroHTML2) {
   EXPECT_EQ(CountVisibleImageRecords(), 0u);
 }
 
+TEST_P(ImagePaintTimingDetectorTest, LargestImagePaint_FullViewportImage) {
+  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
+  SetBodyInnerHTML(R"HTML(
+    <style>body {margin: 0px;}</style>
+    <img id="target"></img>
+  )HTML");
+  SetImageAndPaint("target", 3000, 3000);
+  UpdateAllLifecyclePhasesAndInvokeCallbackIfAny();
+  ImageRecord* record = FindLargestPaintCandidate();
+  EXPECT_FALSE(record);
+  // Simulate some input event to force StopRecordEntries().
+  SimulateKeyDown();
+  auto entries = test_ukm_recorder.GetEntriesByName(UkmPaintTiming::kEntryName);
+  EXPECT_EQ(1ul, entries.size());
+  auto* entry = entries[0];
+  test_ukm_recorder.ExpectEntryMetric(
+      entry, UkmPaintTiming::kLCPDebugging_HasViewportImageName, true);
+}
+
 }  // namespace blink

tools/metrics/ukm/ukm.xml

@@ -2062,6 +2062,21 @@ be describing additional metrics about the same event.
   </metric>
 </event>
 
+<event name="Blink.PaintTiming" singular="True">
+  <owner>npm@chromium.org</owner>
+  <owner>sullivan@chromium.org</owner>
+  <summary>
+    Paint timing metrics recorded in Blink, usually used as debugging metrics
+    for PaintTiming metrics in the PageLoad event.
+  </summary>
+  <metric name="LCPDebugging.HasViewportImage" enum="Boolean">
+    <summary>
+      Records whether a page has an image whose size equals the full viewport.
+      Recorded when the LCP algorithm has stopped.
+    </summary>
+  </metric>
+</event>
+
 <event name="Blink.Script.AsyncScripts" singular="True">
   <owner>dom@chromium.org</owner>
   <owner>chrome-loading@google.com</owner>