Remove expired 'RecordTime' histogram.

Times are small, consistent, and now on a background thread.

Bug: 888748
Change-Id: I93684f43d8a711dcac6d950b6f03dccfa8ba55e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1558130
Commit-Queue: Brian White <bcwhite@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Auto-Submit: Brian White <bcwhite@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#648698}

components/metrics/file_metrics_provider.cc

@@ -636,13 +636,10 @@ bool FileMetricsProvider::ProvideIndependentMetricsOnTaskRunner(
     SystemProfileProto* system_profile_proto,
     base::HistogramSnapshotManager* snapshot_manager) {
   RecordEmbeddedProfileResult(EMBEDDED_PROFILE_ATTEMPT);
-  base::Time start_time = base::Time::Now();
   if (PersistentSystemProfile::GetSystemProfile(
           *source->allocator->memory_allocator(), system_profile_proto)) {
     system_profile_proto->mutable_stability()->set_from_previous_run(true);
     RecordHistogramSnapshotsFromSource(snapshot_manager, source);
-    UMA_HISTOGRAM_TIMES("UMA.FileMetricsProvider.EmbeddedProfile.RecordTime",
-                        base::Time::Now() - start_time);
     RecordEmbeddedProfileResult(EMBEDDED_PROFILE_FOUND);
 
     if (system_profile_proto->hardware().has_cpu()) {

tools/metrics/histograms/histograms.xml

@@ -126351,6 +126351,10 @@ uploading your change for review.
 
 <histogram name="UMA.FileMetricsProvider.EmbeddedProfile.RecordTime" units="ms"
     expires_after="M71">
+  <obsolete>
+    Removed 2019/04 as times are small, consistent, and now on a background
+    thread.
+  </obsolete>
   <owner>bcwhite@chromium.org</owner>
   <summary>
     Tracks the time used to record all histograms from a file with an embedded