Use mockable time in CompositorFrameReporter

This CL adds the possibility to inject a base::TickClock* into
CompositorFrameReporter, so its timing can be mocked by tests.
CompositorFrameReportingController and CompositorFrameReporterTest are
also updated to make use of this.

Bug: 1054009,1057193
Change-Id: I38ab3ebb92b06f5c31e1dbdc514cab29b9791cae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2160408
Commit-Queue: Mohsen Izadi <mohsen@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762122}

cc/metrics/compositor_frame_reporter.cc

@@ -229,6 +229,7 @@ CompositorFrameReporter::CopyReporterAtBeginImplStage() const {
   new_reporter->current_stage_.stage_type =
       StageType::kBeginImplFrameToSendBeginMainFrame;
   new_reporter->current_stage_.start_time = stage_history_.front().start_time;
+  new_reporter->set_tick_clock(tick_clock_);
   return new_reporter;
 }
 
@@ -292,7 +293,7 @@ void CompositorFrameReporter::OnAbortBeginMainFrame(base::TimeTicks timestamp) {
 
 void CompositorFrameReporter::OnDidNotProduceFrame(
     FrameSkippedReason skip_reason) {
-  did_not_produce_frame_time_ = base::TimeTicks::Now();
+  did_not_produce_frame_time_ = Now();
   frame_skip_reason_ = skip_reason;
 }
 
@@ -323,7 +324,7 @@ void CompositorFrameReporter::SetEventsMetrics(
 
 void CompositorFrameReporter::TerminateReporter() {
   if (frame_termination_status_ == FrameTerminationStatus::kUnknown)
-    TerminateFrame(FrameTerminationStatus::kUnknown, base::TimeTicks::Now());
+    TerminateFrame(FrameTerminationStatus::kUnknown, Now());
   DCHECK_EQ(current_stage_.start_time, base::TimeTicks());
   const char* termination_status_str = nullptr;
   switch (frame_termination_status_) {
@@ -723,4 +724,8 @@ base::TimeDelta CompositorFrameReporter::SumOfStageHistory() const {
   return sum;
 }
 
+base::TimeTicks CompositorFrameReporter::Now() const {
+  return tick_clock_->NowTicks();
+}
+
 }  // namespace cc

cc/metrics/compositor_frame_reporter.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/optional.h"
+#include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "cc/base/base_export.h"
 #include "cc/cc_export.h"
@@ -175,6 +176,11 @@ class CC_EXPORT CompositorFrameReporter {
 
   FrameSkippedReason frame_skip_reason() const { return *frame_skip_reason_; }
 
+  void set_tick_clock(const base::TickClock* tick_clock) {
+    DCHECK(tick_clock);
+    tick_clock_ = tick_clock;
+  }
+
  private:
   void TerminateReporter();
   void EndCurrentStage(base::TimeTicks end_time);
@@ -223,6 +229,8 @@ class CC_EXPORT CompositorFrameReporter {
   // This method is only used for DCheck
   base::TimeDelta SumOfStageHistory() const;
 
+  base::TimeTicks Now() const;
+
   const bool should_report_metrics_;
 
   StageData current_stage_;
@@ -261,6 +269,8 @@ class CC_EXPORT CompositorFrameReporter {
   base::Optional<base::TimeTicks> did_not_produce_frame_time_;
   base::Optional<FrameSkippedReason> frame_skip_reason_;
   base::Optional<base::TimeTicks> main_frame_abort_time_;
+
+  const base::TickClock* tick_clock_ = base::DefaultTickClock::GetInstance();
 };
 }  // namespace cc
 

cc/metrics/compositor_frame_reporter_unittest.cc

@@ -10,6 +10,7 @@
 
 #include "base/strings/strcat.h"
 #include "base/test/metrics/histogram_tester.h"
+#include "base/test/simple_test_tick_clock.h"
 #include "cc/input/scroll_input_type.h"
 #include "cc/metrics/compositor_frame_reporting_controller.h"
 #include "cc/metrics/event_metrics.h"
@@ -34,16 +35,17 @@ class CompositorFrameReporterTest : public testing::Test {
             base::TimeTicks() + base::TimeDelta::FromMilliseconds(16),
             nullptr,
             /*should_report_metrics=*/true)) {
+    pipeline_reporter_->set_tick_clock(&test_tick_clock_);
     AdvanceNowByMs(1);
   }
 
  protected:
   base::TimeTicks AdvanceNowByMs(int advance_ms) {
-    now_ += base::TimeDelta::FromMicroseconds(advance_ms);
-    return now_;
+    test_tick_clock_.Advance(base::TimeDelta::FromMicroseconds(advance_ms));
+    return test_tick_clock_.NowTicks();
   }
 
-  base::TimeTicks Now() { return now_; }
+  base::TimeTicks Now() { return test_tick_clock_.NowTicks(); }
 
   viz::FrameTimingDetails BuildFrameTimingDetails() {
     viz::FrameTimingDetails frame_timing_details;
@@ -56,10 +58,11 @@ class CompositorFrameReporterTest : public testing::Test {
     return frame_timing_details;
   }
 
-  std::unique_ptr<CompositorFrameReporter> pipeline_reporter_;
+  // This should be defined before |pipeline_reporter_| so it is created before
+  // and destroyed after that.
+  base::SimpleTestTickClock test_tick_clock_;
 
- private:
-  base::TimeTicks now_;
+  std::unique_ptr<CompositorFrameReporter> pipeline_reporter_;
 };
 
 TEST_F(CompositorFrameReporterTest, MainFrameAbortedReportingTest) {

cc/metrics/compositor_frame_reporting_controller.cc

@@ -67,11 +67,10 @@ void CompositorFrameReportingController::WillBeginImplFrame(
     reporter->TerminateFrame(FrameTerminationStatus::kDidNotProduceFrame,
                              reporter->did_not_produce_frame_time());
   }
-  std::unique_ptr<CompositorFrameReporter> reporter =
-      std::make_unique<CompositorFrameReporter>(
-          active_trackers_, args.frame_id,
-          args.frame_time + (args.interval * 1.5), latency_ukm_reporter_.get(),
-          should_report_metrics_);
+  auto reporter = std::make_unique<CompositorFrameReporter>(
+      active_trackers_, args.frame_id, args.frame_time + (args.interval * 1.5),
+      latency_ukm_reporter_.get(), should_report_metrics_);
+  reporter->set_tick_clock(tick_clock_);
   reporter->StartStage(StageType::kBeginImplFrameToSendBeginMainFrame,
                        begin_time);
   reporters_[PipelineStage::kBeginImplFrame] = std::move(reporter);
@@ -94,11 +93,11 @@ void CompositorFrameReportingController::WillBeginMainFrame(
     // In this case we have already submitted the ImplFrame, but we received
     // beginMain frame before next BeginImplFrame (Not reached the ImplFrame
     // deadline yet). So will start a new reporter at BeginMainFrame.
-    std::unique_ptr<CompositorFrameReporter> reporter =
-        std::make_unique<CompositorFrameReporter>(
+    auto reporter = std::make_unique<CompositorFrameReporter>(
         active_trackers_, args.frame_id,
-            args.frame_time + (args.interval * 1.5),
-            latency_ukm_reporter_.get(), should_report_metrics_);
+        args.frame_time + (args.interval * 1.5), latency_ukm_reporter_.get(),
+        should_report_metrics_);
+    reporter->set_tick_clock(tick_clock_);
     reporter->StartStage(StageType::kSendBeginMainFrameToCommit, Now());
     reporters_[PipelineStage::kBeginMainFrame] = std::move(reporter);
   }

cc/metrics/compositor_frame_reporting_controller.h

@@ -79,6 +79,7 @@ class CC_EXPORT CompositorFrameReportingController {
   virtual void RemoveActiveTracker(FrameSequenceTrackerType type);
 
   void set_tick_clock(const base::TickClock* tick_clock) {
+    DCHECK(tick_clock);
     tick_clock_ = tick_clock;
   }