[cc/metrics] Introduce TotalFrameCounter.

TotalFrameCounter counts the number of vsyncs the compositor was visible
for. This, in combination with DroppedFrameCounter::total_dropped() can
be used to measure the overall dropped-frame metric for the page.

BUG=1115376

Change-Id: I73959aa8ade0ebd56df6a2f31f7f1e171c3f7727
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2233302Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799991}

cc/BUILD.gn

@@ -184,6 +184,8 @@ cc_component("cc") {
     "metrics/lcd_text_metrics_reporter.h",
     "metrics/throughput_ukm_reporter.cc",
     "metrics/throughput_ukm_reporter.h",
+    "metrics/total_frame_counter.cc",
+    "metrics/total_frame_counter.h",
     "metrics/video_playback_roughness_reporter.cc",
     "metrics/video_playback_roughness_reporter.h",
     "raster/bitmap_raster_buffer_provider.cc",
@@ -679,6 +681,7 @@ cc_test("cc_unittests") {
     "metrics/frame_sequence_metrics_unittest.cc",
     "metrics/frame_sequence_tracker_unittest.cc",
     "metrics/jank_metrics_unittest.cc",
+    "metrics/total_frame_counter_unittest.cc",
     "metrics/video_playback_roughness_reporter_unittest.cc",
     "mojo_embedder/async_layer_tree_frame_sink_unittest.cc",
     "paint/clear_for_opaque_raster_unittest.cc",

cc/metrics/dropped_frame_counter.cc

@@ -9,7 +9,6 @@
 #include <limits>
 
 #include "base/memory/ptr_util.h"
-#include "base/metrics/histogram_macros.h"
 
 namespace cc {
 

cc/metrics/dropped_frame_counter.h

@@ -10,7 +10,6 @@
 #include <memory>
 
 #include "base/containers/ring_buffer.h"
-#include "base/time/time.h"
 
 namespace cc {
 
@@ -23,6 +22,7 @@ class DroppedFrameCounter {
     kFrameStatePartial,
     kFrameStateComplete
   };
+
   DroppedFrameCounter();
 
   DroppedFrameCounter(const DroppedFrameCounter&) = delete;

cc/metrics/total_frame_counter.cc

+// Copyright 2020 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 "cc/metrics/total_frame_counter.h"
+
+#include "base/logging.h"
+#include "components/viz/common/frame_sinks/begin_frame_args.h"
+
+namespace cc {
+
+TotalFrameCounter::TotalFrameCounter() = default;
+
+void TotalFrameCounter::OnShow(base::TimeTicks timestamp) {
+  DCHECK(last_shown_timestamp_.is_null());
+  DCHECK(latest_interval_.is_zero());
+  last_shown_timestamp_ = timestamp;
+}
+
+void TotalFrameCounter::OnHide(base::TimeTicks timestamp) {
+  // It is possible to hide right after being shown before receiving any
+  // BeginFrameArgs.
+  if (!latest_interval_.is_zero())
+    UpdateTotalFramesSinceLastVisible(timestamp);
+  last_shown_timestamp_ = base::TimeTicks();
+  latest_interval_ = base::TimeDelta();
+}
+
+void TotalFrameCounter::OnBeginFrame(const viz::BeginFrameArgs& args) {
+  // In tests, it is possible to receive begin-frames when invisible. Ignore
+  // these.
+  if (last_shown_timestamp_.is_null())
+    return;
+
+  if (!latest_interval_.is_zero() && latest_interval_ != args.interval) {
+    UpdateTotalFramesSinceLastVisible(args.frame_time);
+    last_shown_timestamp_ = args.frame_time;
+  }
+
+  latest_interval_ = args.interval;
+}
+
+void TotalFrameCounter::Reset() {
+  total_frames_ = 0;
+  latest_interval_ = {};
+  // If the compositor is visible, then update the visible timestamp to current
+  // time.
+  if (!last_shown_timestamp_.is_null())
+    last_shown_timestamp_ = base::TimeTicks::Now();
+}
+
+void TotalFrameCounter::UpdateTotalFramesSinceLastVisible(
+    base::TimeTicks until) {
+  DCHECK(!until.is_null());
+  DCHECK(!last_shown_timestamp_.is_null());
+  DCHECK_GE(until, last_shown_timestamp_);
+  DCHECK(!latest_interval_.is_zero());
+  auto frames_since =
+      std::round((until - last_shown_timestamp_) / latest_interval_);
+  total_frames_ += frames_since;
+}
+
+}  // namespace cc

cc/metrics/total_frame_counter.h

+// Copyright 2020 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.
+
+#ifndef CC_METRICS_TOTAL_FRAME_COUNTER_H_
+#define CC_METRICS_TOTAL_FRAME_COUNTER_H_
+
+#include "base/time/time.h"
+#include "cc/cc_export.h"
+
+namespace viz {
+struct BeginFrameArgs;
+}
+
+namespace cc {
+
+// This class keeps track of how many vsyncs (frames) the compositor was visible
+// for.
+class CC_EXPORT TotalFrameCounter {
+ public:
+  TotalFrameCounter();
+
+  TotalFrameCounter(const TotalFrameCounter&) = delete;
+  TotalFrameCounter& operator=(const TotalFrameCounter&) = delete;
+
+  void Reset();
+
+  void OnShow(base::TimeTicks timestamp);
+  void OnHide(base::TimeTicks timestamp);
+  void OnBeginFrame(const viz::BeginFrameArgs& args);
+
+  size_t total_frames() const { return total_frames_; }
+
+ private:
+  void UpdateTotalFramesSinceLastVisible(base::TimeTicks until);
+
+  size_t total_frames_ = 0;
+
+  // The most recent vsync-interval set by the display compositor.
+  // Set only if the compositor is currently visible, otherwise not set.
+  base::TimeDelta latest_interval_;
+
+  // The time the compositor was made visible.
+  // Set only if the compositor is currently visible, otherwise not set.
+  base::TimeTicks last_shown_timestamp_;
+};
+
+}  // namespace cc
+
+#endif  // CC_METRICS_TOTAL_FRAME_COUNTER_H_

cc/metrics/total_frame_counter_unittest.cc

+// Copyright 2020 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 "cc/metrics/total_frame_counter.h"
+#include "components/viz/common/frame_sinks/begin_frame_args.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+namespace {
+
+const uint64_t kSourceId = 1;
+
+TEST(TotalFrameCounterTest, Basic) {
+  TotalFrameCounter counter;
+  uint64_t sequence_number = 1;
+  auto frame_time = base::TimeTicks::Now();
+  const auto interval = base::TimeDelta::FromMillisecondsD(16.67);
+
+  auto args = viz::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, kSourceId, sequence_number++, frame_time,
+      frame_time + interval, interval, viz::BeginFrameArgs::NORMAL);
+  counter.OnShow(frame_time);
+  counter.OnBeginFrame(args);
+
+  auto advance = base::TimeDelta::FromSeconds(1);
+  frame_time += advance;
+  counter.OnHide(frame_time);
+  EXPECT_EQ(counter.total_frames(), 60u);
+}
+
+TEST(TotalFrameCounterTest, BeginFrameIntervalChange) {
+  TotalFrameCounter counter;
+  uint64_t sequence_number = 1;
+  auto frame_time = base::TimeTicks::Now();
+  auto interval = base::TimeDelta::FromMillisecondsD(16.67);
+
+  // Make the page visible at the default frame rate.
+  auto args = viz::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, kSourceId, sequence_number++, frame_time,
+      frame_time + interval, interval, viz::BeginFrameArgs::NORMAL);
+  counter.OnShow(frame_time);
+  counter.OnBeginFrame(args);
+
+  // After 10 seconds, change the frame rate to be 120fps.
+  interval = base::TimeDelta::FromMillisecondsD(8.33);
+  frame_time += base::TimeDelta::FromSeconds(10);
+  args = viz::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, kSourceId, sequence_number++, frame_time,
+      frame_time + interval, interval, viz::BeginFrameArgs::NORMAL);
+  counter.OnBeginFrame(args);
+
+  // Hide the page after 10 more seconds.
+  auto advance = base::TimeDelta::FromSeconds(10);
+  frame_time += advance;
+  counter.OnHide(frame_time);
+  EXPECT_EQ(counter.total_frames(), 1800u);
+}
+
+TEST(TotalFrameCounterTest, VisibilityChange) {
+  TotalFrameCounter counter;
+  uint64_t sequence_number = 1;
+  auto frame_time = base::TimeTicks::Now();
+  auto interval = base::TimeDelta::FromMillisecondsD(16.67);
+
+  // Make the page visible at the default frame rate.
+  auto args = viz::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, kSourceId, sequence_number++, frame_time,
+      frame_time + interval, interval, viz::BeginFrameArgs::NORMAL);
+  counter.OnShow(frame_time);
+  counter.OnBeginFrame(args);
+
+  // Hide the page after 10 seconds.
+  frame_time += base::TimeDelta::FromSeconds(10);
+  counter.OnHide(frame_time);
+  EXPECT_EQ(counter.total_frames(), 600u);
+
+  // After 20 more seconds, make the page visible again and keep it visible for
+  // 5 more seconds.
+  frame_time += base::TimeDelta::FromSeconds(20);
+  counter.OnShow(frame_time);
+  args = viz::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, kSourceId, sequence_number++, frame_time,
+      frame_time + interval, interval, viz::BeginFrameArgs::NORMAL);
+  counter.OnBeginFrame(args);
+
+  frame_time += base::TimeDelta::FromSeconds(5);
+  counter.OnHide(frame_time);
+  EXPECT_EQ(counter.total_frames(), 900u);
+}
+
+}  // namespace
+}  // namespace cc

cc/trees/layer_tree_host_impl.cc

@@ -2722,6 +2722,7 @@ bool LayerTreeHostImpl::WillBeginImplFrame(const viz::BeginFrameArgs& args) {
   impl_thread_phase_ = ImplThreadPhase::INSIDE_IMPL_FRAME;
   current_begin_frame_tracker_.Start(args);
   frame_trackers_.NotifyBeginImplFrame(args);
+  total_frame_counter_.OnBeginFrame(args);
 
   if (is_likely_to_require_a_draw_) {
     // Optimistically schedule a draw. This will let us expect the tile manager
@@ -3201,6 +3202,10 @@ void LayerTreeHostImpl::SetVisible(bool visible) {
   if (visible_ == visible)
     return;
   visible_ = visible;
+  if (visible_)
+    total_frame_counter_.OnShow(base::TimeTicks::Now());
+  else
+    total_frame_counter_.OnHide(base::TimeTicks::Now());
   DidVisibilityChange(this, visible_);
   UpdateTileManagerMemoryPolicy(ActualManagedMemoryPolicy());
 
@@ -4816,6 +4821,7 @@ void LayerTreeHostImpl::SetActiveURL(const GURL& url, ukm::SourceId source_id) {
     // The source id has already been associated to the URL.
     ukm_manager_->SetSourceId(source_id);
   }
+  total_frame_counter_.Reset();
 }
 
 void LayerTreeHostImpl::AllocateLocalSurfaceId() {

cc/trees/layer_tree_host_impl.h

@@ -36,6 +36,7 @@
 #include "cc/metrics/event_metrics.h"
 #include "cc/metrics/events_metrics_manager.h"
 #include "cc/metrics/frame_sequence_tracker_collection.h"
+#include "cc/metrics/total_frame_counter.h"
 #include "cc/paint/discardable_image_map.h"
 #include "cc/paint/paint_worklet_job.h"
 #include "cc/resources/ui_resource_client.h"
@@ -87,6 +88,7 @@ class BrowserControlsOffsetManager;
 class CompositorFrameReportingController;
 class DebugRectHistory;
 class EvictionTilePriorityQueue;
+class DroppedFrameCounter;
 class ImageAnimationController;
 class LCDTextMetricsReporter;
 class LayerImpl;
@@ -1065,6 +1067,8 @@ class CC_EXPORT LayerTreeHostImpl : public InputHandler,
   std::unique_ptr<PageScaleAnimation> page_scale_animation_;
 
   DroppedFrameCounter dropped_frame_counter_;
+  TotalFrameCounter total_frame_counter_;
+
   std::unique_ptr<MemoryHistory> memory_history_;
   std::unique_ptr<DebugRectHistory> debug_rect_history_;