Removed or extended FileMetricsProvider metrics.

Timing metrics were removed as they're consistently very small.
Result metrics were extended as they're can reflect sudden changes in
the underlying operations.

Bug: 975059
Change-Id: Ic982ad8d5e1fdcf48d5a1600adcda95bfae4f3a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1664515
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Auto-Submit: Brian White <bcwhite@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#670421}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 219e37e96bd411ee6ba22aef7d84067f87e26972
diff --git a/file_metrics_provider.cc b/file_metrics_provider.cc
index 06d1fc2..9e6b787 100644
--- a/file_metrics_provider.cc
+++ b/file_metrics_provider.cc
@@ -517,7 +517,6 @@
 // static
 void FileMetricsProvider::MergeHistogramDeltasFromSource(SourceInfo* source) {
   DCHECK(source->allocator);
-  SCOPED_UMA_HISTOGRAM_TIMER("UMA.FileMetricsProvider.SnapshotTime.File");
   base::PersistentHistogramAllocator::Iterator histogram_iter(
       source->allocator.get());
 
@@ -782,8 +781,6 @@
   // Check all sources for previous run to see if they need to be read.
   for (auto iter = sources_for_previous_run_.begin();
        iter != sources_for_previous_run_.end();) {
-    SCOPED_UMA_HISTOGRAM_TIMER("UMA.FileMetricsProvider.InitialCheckTime.File");
-
     auto temp = iter++;
     SourceInfo* source = temp->get();
 
@@ -828,9 +825,6 @@
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
   for (const std::unique_ptr<SourceInfo>& source : sources_for_previous_run_) {
-    SCOPED_UMA_HISTOGRAM_TIMER(
-        "UMA.FileMetricsProvider.InitialSnapshotTime.File");
-
     // The source needs to have an allocator attached to it in order to read
     // histograms out of it.
     DCHECK(!source->read_complete);