[CSSTypedOM] Computed StylePropertyMap use ComputedStyle for Lengths

third_party/WebKit/Source/core/css/cssom/ComputedStylePropertyMap.h

 // Copyright 2016 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 ComputedStylePropertyMap_h
 #define ComputedStylePropertyMap_h
 
 #include "core/css/CSSComputedStyleDeclaration.h"
 #include "core/css/cssom/ImmutableStylePropertyMap.h"
+#include "core/dom/Node.h"
+#include "core/layout/LayoutObject.h"
 
 namespace blink {
 
 class CORE_EXPORT ComputedStylePropertyMap : public ImmutableStylePropertyMap {
   WTF_MAKE_NONCOPYABLE(ComputedStylePropertyMap);
 
  public:
-  static ComputedStylePropertyMap* create(
-      CSSComputedStyleDeclaration* computedStyleDeclaration) {
-    return new ComputedStylePropertyMap(computedStyleDeclaration);
+  static ComputedStylePropertyMap* create(Node* node,
+                                          const String& pseudoElement) {
+    return new ComputedStylePropertyMap(node, pseudoElement);
   }
 
   Vector<String> getProperties() override;
 
   DEFINE_INLINE_VIRTUAL_TRACE() {
     visitor->trace(m_computedStyleDeclaration);
+    visitor->trace(m_node);
     ImmutableStylePropertyMap::trace(visitor);
   }
 
+ private:
+  Node* node() const;
+
  protected:
-  ComputedStylePropertyMap(
-      CSSComputedStyleDeclaration* computedStyleDeclaration)
+  ComputedStylePropertyMap(Node* node, const String& pseudoElement = String())
       : ImmutableStylePropertyMap(),
-        m_computedStyleDeclaration(computedStyleDeclaration) {}
+        m_computedStyleDeclaration(
+            CSSComputedStyleDeclaration::create(node, false, pseudoElement)),
+        m_pseudoId(CSSSelector::parsePseudoId(pseudoElement)),
+        m_node(node) {}
 
   CSSStyleValueVector getAllInternal(CSSPropertyID) override;
   CSSStyleValueVector getAllInternal(AtomicString customPropertyName) override;
 
   HeapVector<StylePropertyMapEntry> getIterationEntries() override {
     return HeapVector<StylePropertyMapEntry>();
   }
 
-  Member<CSSStyleDeclaration> m_computedStyleDeclaration;
+  Member<CSSComputedStyleDeclaration> m_computedStyleDeclaration;
+  PseudoId m_pseudoId;
+  Member<Node> m_node;

[sashab, 2017/01/17 01:12:38]

Basically here's how I feel about passing around Node*:

- We should make it const in as many places as we can
- We should make it explicitly non-null in methods that cannot return a nullptr

Otherwise callers will make assumptions about the returned type (e.g. modify it,
or check if its null) when that can never be true.

If you'd rather do it in a follow up patch, then add a TODO here saying:
// TODO(rjwright): Make this Member<const Node>

And add a TODO above the node() method:
// TODO(rjwright): Make this return a Node&.

And add a DCHECK(node) to the constructor (since I'm pretty sure it can never be
null).

Technically this is bad design so like I said I'd much prefer if you did the
changes in this patch. Yes it's a nontrivial change but its really important to
the health and readability of this code. Alternatively you can upload a second
patch with this one as a dependent patchset, and we can land this one once both
are working. Either way I want to see progress on this.

 };
 
 }  // namespace blink
 
 #endif