Removed UseCounters to avoid redundancy in metrics.

Removed the UseCounters kScrollbarUseVerticalScrollbarThumb and
kScrollbarUseHorizontalScrollbarThumb to avoid redundancy in metrics
with the 4 UseCounters that were added here:
https://chromium-review.googlesource.com/c/chromium/src/+/1575822/7

Bug: 954359
Change-Id: I1f9552b38bb86fb97c617e55bbfd9e72fe03a248
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663039Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Allison Pastewka <alpastew@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#670196}

third_party/blink/public/mojom/web_feature/web_feature.mojom

@@ -1260,10 +1260,8 @@ enum WebFeature {
   kV8PromiseConstructorReturnedUndefined = 1766,
   kFormSubmittedWithUnclosedFormControl = 1767,
   kScrollbarUseVerticalScrollbarButton = 1777,
-  kScrollbarUseVerticalScrollbarThumb = 1778,
   kScrollbarUseVerticalScrollbarTrack = 1779,
   kScrollbarUseHorizontalScrollbarButton = 1780,
-  kScrollbarUseHorizontalScrollbarThumb = 1781,
   kScrollbarUseHorizontalScrollbarTrack = 1782,
   kHTMLTableCellElementColspan = 1783,
   kHTMLTableCellElementColspanGreaterThan1000 = 1784,

third_party/blink/renderer/core/paint/paint_layer_scrollable_area.cc

@@ -2842,10 +2842,17 @@ void PaintLayerScrollableArea::DidScrollWithScrollbar(
                : WebFeature::kScrollbarUseHorizontalScrollbarButton);
       break;
     case kThumbPart:
-      scrollbar_use_uma =
-          (orientation == kVerticalScrollbar
-               ? WebFeature::kScrollbarUseVerticalScrollbarThumb
-               : WebFeature::kScrollbarUseHorizontalScrollbarThumb);
+      if (orientation == kVerticalScrollbar) {
+        scrollbar_use_uma =
+            (WebInputEvent::IsMouseEventType(type)
+                 ? WebFeature::kVerticalScrollbarThumbScrollingWithMouse
+                 : WebFeature::kVerticalScrollbarThumbScrollingWithTouch);
+      } else {
+        scrollbar_use_uma =
+            (WebInputEvent::IsMouseEventType(type)
+                 ? WebFeature::kHorizontalScrollbarThumbScrollingWithMouse
+                 : WebFeature::kHorizontalScrollbarThumbScrollingWithTouch);
+      }
       break;
     case kBackTrackPart:
     case kForwardTrackPart:
@@ -2860,24 +2867,7 @@ void PaintLayerScrollableArea::DidScrollWithScrollbar(
 
   Document& document = GetLayoutBox()->GetDocument();
 
-  // TODO(alpastew): Remove the UseCounters kScrollbarUseVerticalScrollbarThumb
-  // and kScrollbarUseHorizontalScrollbarThumb to avoid redundancy in metrics.
   UseCounter::Count(document, scrollbar_use_uma);
-
-  if (scrollbar_use_uma == WebFeature::kScrollbarUseVerticalScrollbarThumb) {
-    WebFeature input_specific_uma =
-        (WebInputEvent::IsMouseEventType(type)
-             ? WebFeature::kVerticalScrollbarThumbScrollingWithMouse
-             : WebFeature::kVerticalScrollbarThumbScrollingWithTouch);
-    UseCounter::Count(document, input_specific_uma);
-  } else if (scrollbar_use_uma ==
-             WebFeature::kScrollbarUseHorizontalScrollbarThumb) {
-    WebFeature input_specific_uma =
-        (WebInputEvent::IsMouseEventType(type)
-             ? WebFeature::kHorizontalScrollbarThumbScrollingWithMouse
-             : WebFeature::kHorizontalScrollbarThumbScrollingWithTouch);
-    UseCounter::Count(document, input_specific_uma);
-  }
 }
 
 CompositorElementId PaintLayerScrollableArea::GetCompositorElementId() const {