Revert "Implement a Hit Test Cache for same point hits."

Source/core/layout/HitTestCache.cpp

Index: Source/core/layout/HitTestCache.cpp
diff --git a/Source/core/layout/HitTestCache.cpp b/Source/core/layout/HitTestCache.cpp
deleted file mode 100644
index 25f6957a1d4e19c92d3da74fcd00326d78795315..0000000000000000000000000000000000000000
--- a/Source/core/layout/HitTestCache.cpp
+++ /dev/null
@@ -1,80 +0,0 @@
-// Copyright (c) 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "config.h"
-#include "core/layout/HitTestCache.h"
-
-#include "public/platform/Platform.h"
-
-namespace blink {
-
-bool HitTestCache::lookupCachedResult(HitTestResult& hitResult, uint64_t domTreeVersion)
-{
-    bool result = false;
-    HitHistogramMetric metric = HitHistogramMetric::MISS;
-    if (hitResult.hitTestRequest().avoidCache()) {
-        metric = HitHistogramMetric::MISS_EXPLICIT_AVOID;
-    // For now we don't support rect based hit results.
-    } else if (domTreeVersion == m_domTreeVersion && !hitResult.hitTestLocation().isRectBasedTest()) {
-        for (const auto& cachedItem : m_items) {
-            if (cachedItem.validityRect().contains(hitResult.hitTestLocation().point())) {
-                if (hitResult.hitTestRequest().equalForCacheability(cachedItem.hitTestRequest())) {
-                    metric = hitResult.hitTestLocation().point() == cachedItem.hitTestLocation().point() ? HitHistogramMetric::HIT_EXACT_MATCH : HitHistogramMetric::HIT_REGION_MATCH;
-                    result = true;
-                    hitResult = cachedItem;
-                    break;
-                }
-                metric = HitHistogramMetric::MISS_VALIDITY_RECT_MATCHES;
-            }
-        }
-    }
-    Platform::current()->histogramEnumeration("Event.HitTest", static_cast<int>(metric), static_cast<int>(HitHistogramMetric::MAX_HIT_METRIC));
-    return result;
-}
-
-void HitTestCache::verifyCachedResult(const HitTestResult& expected, const HitTestResult& actual)
-{
-    bool pointMatch = actual.hitTestLocation().point() == expected.hitTestLocation().point();
-
-    ValidityHistogramMetric metric;
-    if (!actual.equalForCacheability(expected)) {
-        if (pointMatch) {
-            metric = expected.hitTestLocation().isRectBasedTest() ? ValidityHistogramMetric::INCORRECT_RECT_BASED_EXACT_MATCH : ValidityHistogramMetric::INCORRECT_POINT_EXACT_MATCH;
-        } else {
-            metric = expected.hitTestLocation().isRectBasedTest() ? ValidityHistogramMetric::INCORRECT_RECT_BASED_REGION : ValidityHistogramMetric::INCORRECT_POINT_REGION;
-        }
-
-        // ASSERT that the cache hit is the same as the actual result.
-        ASSERT_NOT_REACHED();
-    } else {
-        metric = pointMatch ? ValidityHistogramMetric::VALID_EXACT_MATCH : ValidityHistogramMetric::VALID_REGION;
-    }
-    Platform::current()->histogramEnumeration("Event.HitTestValidity", static_cast<int>(metric), static_cast<int>(ValidityHistogramMetric::MAX_VALIDITY_METRIC));
-}
-
-void HitTestCache::addCachedResult(const HitTestResult& result, uint64_t domTreeVersion)
-{
-    // For now we don't support rect based hit results.
-    if (result.hitTestLocation().isRectBasedTest())
-        return;
-    if (domTreeVersion != m_domTreeVersion)
-        clear();
-    if (m_items.size() < HIT_TEST_CACHE_SIZE)
-        m_items.resize(m_updateIndex + 1);
-
-    m_items.at(m_updateIndex).cacheValues(result);
-    m_domTreeVersion = domTreeVersion;
-
-    m_updateIndex++;
-    if (m_updateIndex >= HIT_TEST_CACHE_SIZE)
-        m_updateIndex = 0;
-}
-
-void HitTestCache::clear()
-{
-    m_updateIndex = 0;
-    m_items.clear();
-}
-
-} // namespace blink