Removed ReportOffsetBetweenDeadlineAndPresentationTime metric

CompositorLatency.Diagnostic.PresentationTimeDeltaFromDeadline we being
recorded to validate the assumption that most presented frames would be
reported close to the deadline. As reported values confirm this
assumption we do not need to track this values anymore, so this change
removes this metric.

Bug: 1125656
Change-Id: Ic2ab96609577c91d71d402a114d22f3df14cf86e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527622Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Weilun Shi <sweilun@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Behdad Bakhshinategh <behdadb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826294}

cc/metrics/compositor_frame_reporter.cc

@@ -241,19 +241,6 @@ base::TimeTicks ComputeSafeDeadlineForFrame(const viz::BeginFrameArgs& args) {
   return args.frame_time + (args.interval * 1.5);
 }
 
-void ReportOffsetBetweenDeadlineAndPresentationTime(
-    const viz::BeginFrameArgs& args,
-    base::TimeTicks presentation_time) {
-  const base::TimeTicks strict_deadline = args.frame_time + args.interval;
-  const base::TimeDelta offset = presentation_time - strict_deadline;
-  // |strict_deadline| and |presentation_time| should normally be pretty close.
-  // Measure how close they are.
-  UMA_HISTOGRAM_CUSTOM_TIMES(
-      "CompositorLatency.Diagnostic.PresentationTimeDeltaFromDeadline", offset,
-      base::TimeDelta::FromMilliseconds(1),
-      base::TimeDelta::FromMilliseconds(32), /*bucket_count=*/16);
-}
-
 #define REPORT_VIZ_TRACE_EVENT(start_time, end_time, index, trace_func) \
   if (start_time <= end_time) {                                         \
     const char* substage_name =                                         \
@@ -438,8 +425,6 @@ void CompositorFrameReporter::TerminateReporter() {
   switch (frame_termination_status_) {
     case FrameTerminationStatus::kPresentedFrame:
       EnableReportType(FrameReportType::kNonDroppedFrame);
-      ReportOffsetBetweenDeadlineAndPresentationTime(args_,
-                                                     frame_termination_time_);
       if (ComputeSafeDeadlineForFrame(args_) < frame_termination_time_)
         EnableReportType(FrameReportType::kMissedDeadlineFrame);
       break;

tools/metrics/histograms/histograms_xml/others/histograms.xml

@@ -2513,6 +2513,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 <histogram
     name="CompositorLatency.Diagnostic.PresentationTimeDeltaFromDeadline"
     units="ms" expires_after="M87">
+  <obsolete>
+    Removed in M88.
+  </obsolete>
   <owner>behdadb@chromium.org</owner>
   <owner>sadrul@chromium.org</owner>
   <summary>