Oilpan: fix build after r197063, move HitTestCache to the heap.

Source/core/layout/HitTestCache.h

 // 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.
 
 #ifndef HitTestCache_h
 #define HitTestCache_h
 
 #include "core/layout/HitTestResult.h"
+#include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 // This object implements a cache for storing successful hit tests to DOM nodes
 // in the visible viewport. The cache is cleared on dom modifications,
 // scrolling, CSS style modifications.
 //
 // Multiple hit tests can occur when processing events. Typically the DOM doesn't
 // change when each event is processed so in order to decrease the time spent
 // processing the events a hit cache is useful. For example a GestureTap event
 // will generate a series of simulated mouse events (move, down, up, click)
 // with the same co-ordinates and ideally we'd like to do the hit test once
 // and use the result for the targetting of each event.
 //
 // Some of the related design, motivation can be found in:
 // https://docs.google.com/document/d/1b0NYAD4S9BJIpHGa4JD2HLmW28f2rUh1jlqrgpU3zVU/
 //
 
 // A cache size of 2 is used because it is relatively cheap to store;
 // and the ping-pong behaviour of some of the HitTestRequest flags during
 // Mouse/Touch/Pointer events can generate increased cache misses with
 // size of 1.
 #define HIT_TEST_CACHE_SIZE (2)
 
-class HitTestCache {
+class HitTestCache final : public NoBaseWillBeGarbageCollectedFinalized<HitTestCache> {
 public:
-    HitTestCache() = default;
+    static PassOwnPtrWillBeRawPtr<HitTestCache> create()
+    {
+        return adoptPtrWillBeNoop(new HitTestCache);
+    }
 
     // Check the cache for a possible hit and update |result| if
     // hit encountered; returning true. Otherwise false.
     bool lookupCachedResult(HitTestResult&, uint64_t domTreeVersion);
 
     void clear();
 
     // Verify that the |actual| object matches the |expected| object; and
     // log UMA metrics indicating the result.
     static void verifyCachedResult(const HitTestResult& expected, const HitTestResult& actual);
 
     // Adds a HitTestResult to the cache.
     void addCachedResult(const HitTestResult&, uint64_t domTreeVersion);
 
+    DECLARE_TRACE();
+
 private:
+    HitTestCache() = default;
+
     // These values are reported in UMA as the "EventHitTest" enumeration.
     // Do not reorder, append new values at the end, deprecate old
     // values and update histograms.xml.
     enum class HitHistogramMetric {
         MISS, // Miss, not found in cache.
         MISS_EXPLICIT_AVOID, // Miss, calle asked to explicitly avoid cache.
         MISS_VALIDITY_RECT_MATCHES, // Miss, validity region matches, type doesn't.
         HIT_EXACT_MATCH, // Hit, exact point matches.
         HIT_REGION_MATCH, // Hit, validity region matches.
         MAX_HIT_METRIC = HIT_REGION_MATCH,
@@ skipping 13 matching lines @@
     };
 
     unsigned m_updateIndex = 0;
     WillBeHeapVector<HitTestResult, HIT_TEST_CACHE_SIZE> m_items;
     uint64_t m_domTreeVersion = 0;
 };
 
 } // namespace blink
 
 #endif // HitTestCache_h