Remove unused histogram.

R=mkwst@chromium.org

Bug: 708041
Change-Id: Ib049e39a0d8bd33b7625273614e5ad28dbb26937
Reviewed-on: https://chromium-review.googlesource.com/565403Reviewed-by: Mike West <mkwst@chromium.org>
Reviewed-by: Alexei Svitkine (slow) <asvitkine@chromium.org>
Commit-Queue: Daniel Vogelheim <vogelheim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486713}

third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp

@@ -62,14 +62,6 @@ namespace blink {
 
 namespace {
 
-// Events for UMA. Do not reorder or delete. Add new events at the end, but
-// before SriResourceIntegrityMismatchEventCount.
-enum SriResourceIntegrityMismatchEvent {
-  kCheckingForIntegrityMismatch = 0,
-  kRefetchDueToIntegrityMismatch = 1,
-  kSriResourceIntegrityMismatchEventCount
-};
-
 #define DEFINE_SINGLE_RESOURCE_HISTOGRAM(prefix, name)                      \
   case Resource::k##name: {                                                 \
     DEFINE_THREAD_SAFE_STATIC_LOCAL(                                        \
@@ -110,14 +102,6 @@ void AddRedirectsToTimingInfo(Resource* resource, ResourceTimingInfo* info) {
   }
 }
 
-void RecordSriResourceIntegrityMismatchEvent(
-    SriResourceIntegrityMismatchEvent event) {
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(EnumerationHistogram, integrity_histogram,
-                                  ("sri.resource_integrity_mismatch_event",
-                                   kSriResourceIntegrityMismatchEventCount));
-  integrity_histogram.Count(event);
-}
-
 ResourceLoadPriority TypeToPriority(Resource::Type type) {
   switch (type) {
     case Resource::kMainResource:
@@ -911,7 +895,6 @@ Resource* ResourceFetcher::MatchPreload(const FetchParameters& params,
 
   Resource* resource = it->value;
 
-  RecordSriResourceIntegrityMismatchEvent(kCheckingForIntegrityMismatch);
   if (resource->MustRefetchDueToIntegrityMetadata(params))
     return nullptr;
 
@@ -1029,9 +1012,7 @@ ResourceFetcher::DetermineRevalidationPolicy(
   // resource must be made to get the raw data. This is expected to be an
   // uncommon case, however, as it implies two same-origin requests to the same
   // resource, but with different integrity metadata.
-  RecordSriResourceIntegrityMismatchEvent(kCheckingForIntegrityMismatch);
   if (existing_resource->MustRefetchDueToIntegrityMetadata(fetch_params)) {
-    RecordSriResourceIntegrityMismatchEvent(kRefetchDueToIntegrityMismatch);
     return kReload;
   }
 

tools/metrics/histograms/histograms.xml

@@ -74169,6 +74169,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="sri.resource_integrity_mismatch_event"
     enum="SRIResourceIntegrityMismatchEvent">
+  <obsolete>
+    Removed 07/2017. Reference: crbug.com/708041
+  </obsolete>
   <owner>jww@chromium.org</owner>
   <summary>
     When resources are checked for mismatching integrity and whether the