Change cc::ElementId to be a uint64_t

third_party/WebKit/Source/platform/graphics/CompositorElementId.h

Index: third_party/WebKit/Source/platform/graphics/CompositorElementId.h
diff --git a/third_party/WebKit/Source/platform/graphics/CompositorElementId.h b/third_party/WebKit/Source/platform/graphics/CompositorElementId.h
index 7a17e46a932681b5b9bdd6454c6d20fa3ae7f409..256978f0a1780b1350fac2414acbf4301d11e24c 100644
--- a/third_party/WebKit/Source/platform/graphics/CompositorElementId.h
+++ b/third_party/WebKit/Source/platform/graphics/CompositorElementId.h
@@ -13,46 +13,27 @@
 
 namespace blink {
 
-enum class CompositorSubElementId {
-  kPrimary,
-  kScroll,
-  kViewport,
-  kLinkHighlight
+// Do not add more of these without adjusting the bitfield arithmetic in
+// CreateCompositorElementId.
+enum CompositorSubElementId {
+  kPrimary = 0,
+  kScroll = 1,
+  kViewport = 2,
+  kLinkHighlight = 3,
+  kNumSubElementTypes = 4
 };
 
 using CompositorElementId = cc::ElementId;
+static const CompositorElementId kInvalidElementId = 0;
 
 CompositorElementId PLATFORM_EXPORT
-CreateCompositorElementId(int dom_node_id, CompositorSubElementId);
-
-// Note cc::ElementId has a hash function already implemented via
-// ElementIdHash::operator(). However for consistency's sake we choose to use
-// Blink's hash functions with Blink specific data structures.
-struct CompositorElementIdHash {
-  static unsigned GetHash(const CompositorElementId& p) {
-    return WTF::HashInts(p.primaryId, p.secondaryId);
-  }
-  static bool Equal(const CompositorElementId& a,
-                    const CompositorElementId& b) {
-    return a.primaryId == b.primaryId && a.secondaryId == b.secondaryId;
-  }
-  static const bool safe_to_compare_to_empty_or_deleted = true;
-};
+CreateCompositorElementId(uint64_t dom_node_id, CompositorSubElementId);
 
-struct CompositorElementIdHashTraits
-    : WTF::GenericHashTraits<CompositorElementId> {
-  static CompositorElementId EmptyValue() { return CompositorElementId(); }
-  static void ConstructDeletedValue(CompositorElementId& slot, bool) {
-    slot = CompositorElementId(-1, -1);
-  }
-  static bool IsDeletedValue(CompositorElementId value) {
-    return value == CompositorElementId(-1, -1);
-  }
-};
+uint64_t PLATFORM_EXPORT DomNodeIdFromCompositorElementId(CompositorElementId);
+CompositorSubElementId PLATFORM_EXPORT
+    SubElementIdFromCompositorElementId(CompositorElementId);
 
-using CompositorElementIdSet = HashSet<CompositorElementId,
-                                       CompositorElementIdHash,
-                                       CompositorElementIdHashTraits>;
+using CompositorElementIdSet = HashSet<CompositorElementId>;
 
 }  // namespace blink