Remove some PreloadScanner count histograms

The histograms downsides (memory, binary size, server resources) probably
outweigh their value.

Bug: 809334
Change-Id: I8965007e67275d615abd3dba3a1505d99024a44f
Reviewed-on: https://chromium-review.googlesource.com/904263Reviewed-by: Yoav Weiss <yoav@yoav.ws>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534733}

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

@@ -1296,8 +1296,6 @@ bool ResourceFetcher::IsPreloadedForTest(const KURL& url) const {
 }
 
 void ResourceFetcher::ClearPreloads(ClearPreloadsPolicy policy) {
-  LogPreloadStats(policy);
-
   Vector<PreloadKey> keys_to_be_removed;
   for (const auto& pair : preloads_) {
     Resource* resource = pair.value;
@@ -1600,153 +1598,6 @@ void ResourceFetcher::ReloadLoFiImages() {
   }
 }
 
-void ResourceFetcher::LogPreloadStats(ClearPreloadsPolicy policy) {
-  unsigned scripts = 0;
-  unsigned script_misses = 0;
-  unsigned stylesheets = 0;
-  unsigned stylesheet_misses = 0;
-  unsigned images = 0;
-  unsigned image_misses = 0;
-  unsigned fonts = 0;
-  unsigned font_misses = 0;
-  unsigned medias = 0;
-  unsigned media_misses = 0;
-  unsigned text_tracks = 0;
-  unsigned text_track_misses = 0;
-  unsigned imports = 0;
-  unsigned import_misses = 0;
-  unsigned raws = 0;
-  unsigned raw_misses = 0;
-  for (const auto& pair : preloads_) {
-    Resource* resource = pair.value;
-    // Do not double count link rel preloads. These do not get cleared if the
-    // ClearPreloadsPolicy is only clearing speculative markup preloads.
-    if (resource->IsLinkPreload() &&
-        policy == kClearSpeculativeMarkupPreloads) {
-      continue;
-    }
-    int miss_count = resource->IsUnusedPreload() ? 1 : 0;
-    switch (resource->GetType()) {
-      case Resource::kImage:
-        images++;
-        image_misses += miss_count;
-        break;
-      case Resource::kScript:
-        scripts++;
-        script_misses += miss_count;
-        break;
-      case Resource::kCSSStyleSheet:
-        stylesheets++;
-        stylesheet_misses += miss_count;
-        break;
-      case Resource::kFont:
-        fonts++;
-        font_misses += miss_count;
-        break;
-      case Resource::kAudio:
-      case Resource::kVideo:
-        medias++;
-        media_misses += miss_count;
-        break;
-      case Resource::kTextTrack:
-        text_tracks++;
-        text_track_misses += miss_count;
-        break;
-      case Resource::kImportResource:
-        imports++;
-        import_misses += miss_count;
-        break;
-      case Resource::kRaw:
-        raws++;
-        raw_misses += miss_count;
-        break;
-      case Resource::kMock:
-        // Do not count Resource::Mock because this type is only for testing.
-        break;
-      default:
-        NOTREACHED();
-    }
-  }
-
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, image_preloads,
-                                  ("PreloadScanner.Counts2.Image", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, image_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Image", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, script_preloads,
-      ("PreloadScanner.Counts2.Script", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, script_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Script", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, stylesheet_preloads,
-      ("PreloadScanner.Counts2.CSSStyleSheet", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, stylesheet_preload_misses,
-      ("PreloadScanner.Counts2.Miss.CSSStyleSheet", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, font_preloads,
-                                  ("PreloadScanner.Counts2.Font", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, font_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Font", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, media_preloads,
-                                  ("PreloadScanner.Counts2.Media", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, media_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Media", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, text_track_preloads,
-      ("PreloadScanner.Counts2.TextTrack", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, text_track_preload_misses,
-      ("PreloadScanner.Counts2.Miss.TextTrack", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, import_preloads,
-      ("PreloadScanner.Counts2.Import", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, import_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Import", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, raw_preloads,
-                                  ("PreloadScanner.Counts2.Raw", 0, 100, 25));
-  DEFINE_THREAD_SAFE_STATIC_LOCAL(
-      CustomCountHistogram, raw_preload_misses,
-      ("PreloadScanner.Counts2.Miss.Raw", 0, 100, 25));
-
-  if (images)
-    image_preloads.Count(images);
-  if (image_misses)
-    image_preload_misses.Count(image_misses);
-  if (scripts)
-    script_preloads.Count(scripts);
-  if (script_misses)
-    script_preload_misses.Count(script_misses);
-  if (stylesheets)
-    stylesheet_preloads.Count(stylesheets);
-  if (stylesheet_misses)
-    stylesheet_preload_misses.Count(stylesheet_misses);
-  if (fonts)
-    font_preloads.Count(fonts);
-  if (font_misses)
-    font_preload_misses.Count(font_misses);
-  if (medias)
-    media_preloads.Count(medias);
-  if (media_misses)
-    media_preload_misses.Count(media_misses);
-  if (text_tracks)
-    text_track_preloads.Count(text_tracks);
-  if (text_track_misses)
-    text_track_preload_misses.Count(text_track_misses);
-  if (imports)
-    import_preloads.Count(imports);
-  if (import_misses)
-    import_preload_misses.Count(import_misses);
-  if (raws)
-    raw_preloads.Count(raws);
-  if (raw_misses)
-    raw_preload_misses.Count(raw_misses);
-}
-
 String ResourceFetcher::GetCacheIdentifier() const {
   if (Context().IsControlledByServiceWorker())
     return String::Number(Context().ServiceWorkerID());

tools/metrics/histograms/histograms.xml

@@ -67256,11 +67256,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="PreloadScanner.Counts2" units="preloads">
+  <obsolete>
+    Removed Feb 2018, no longer useful.
+  </obsolete>
   <owner>csharrison@chromium.org</owner>
   <summary>The number of preloads generated by the preload scanner.</summary>
 </histogram>
 
 <histogram name="PreloadScanner.Counts2.Miss" units="preloads">
+  <obsolete>
+    Removed Feb 2018, no longer useful.
+  </obsolete>
   <owner>csharrison@chromium.org</owner>
   <summary>
     The number of unused preloads generated by the preload scanner. Note that