Change CSSParserContext to have a Document handle (vs UseCounter).

third_party/WebKit/Source/core/css/parser/CSSParserContext.h

Index: third_party/WebKit/Source/core/css/parser/CSSParserContext.h
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserContext.h b/third_party/WebKit/Source/core/css/parser/CSSParserContext.h
index 33381ecce41b7447d33c8a54b1fa59f0ff065544..b57136ea48a46fcbb1238bee87e91600fb268ce1 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserContext.h
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserContext.h
@@ -7,6 +7,8 @@
 
 #include "core/CoreExport.h"
 #include "core/css/parser/CSSParserMode.h"
+#include "core/dom/Document.h"
+#include "core/frame/UseCounter.h"
 #include "platform/loader/fetch/ResourceLoaderOptions.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/Referrer.h"
@@ -14,9 +16,7 @@
 namespace blink {
 
 class CSSStyleSheet;
-class Document;
 class StyleSheetContents;
-class UseCounter;
 
 class CORE_EXPORT CSSParserContext
     : public GarbageCollectedFinalized<CSSParserContext> {
@@ -25,7 +25,7 @@ class CORE_EXPORT CSSParserContext
   enum SelectorProfile { DynamicProfile, StaticProfile };
 
   // All three of these factories copy the context and override the current
-  // UseCounter handle.
+  // Document handle used for UseCounter.
   static CSSParserContext* createWithStyleSheet(const CSSParserContext*,
                                                 const CSSStyleSheet*);
   static CSSParserContext* createWithStyleSheetContents(
@@ -34,20 +34,19 @@ class CORE_EXPORT CSSParserContext
   // FIXME: This constructor shouldn't exist if we properly piped the UseCounter
   // through the CSS subsystem. Currently the UseCounter life time is too crazy
   // and we need a way to override it.
-  static CSSParserContext* create(const CSSParserContext* other, UseCounter*);
+  static CSSParserContext* create(const CSSParserContext* other,
+                                  const Document* useCounterDocument);
 
   static CSSParserContext* create(CSSParserMode,
                                   SelectorProfile = DynamicProfile,
-                                  UseCounter* = nullptr);
-  // FIXME: We shouldn't need the UseCounter argument as we could infer it from
-  // the Document but some callers want to disable use counting (e.g. the
-  // WebInspector).
-  static CSSParserContext* create(const Document&, UseCounter*);
+                                  const Document* useCounterDocument = nullptr);
+  static CSSParserContext* create(const Document&,
+                                  const Document* useCounterDocument);
   static CSSParserContext* create(const Document&,
                                   const KURL& baseURLOverride = KURL(),
                                   const String& charset = emptyString,
                                   SelectorProfile = DynamicProfile,
-                                  UseCounter* = nullptr);
+                                  const Document* useCounterDocument = nullptr);
 
   bool operator==(const CSSParserContext&) const;
   bool operator!=(const CSSParserContext& other) const {
@@ -80,16 +79,16 @@ class CORE_EXPORT CSSParserContext
 
   KURL completeURL(const String& url) const;
 
-  // This may return nullptr if counting is disabled.
-  // See comments on constructors.
-  UseCounter* useCounter() const { return m_useCounter; }
-  bool isUseCounterRecordingEnabled() const { return m_useCounter; }
+  void count(UseCounter::Feature) const;
+  void count(CSSParserMode, CSSPropertyID) const;
+  bool isUseCounterRecordingEnabled() const { return m_useCounterDocument; }
+  bool isUseCounterDocumentHandleEqual(const Document* other) const;
 
   ContentSecurityPolicyDisposition shouldCheckContentSecurityPolicy() const {
     return m_shouldCheckContentSecurityPolicy;
   }
 
-  DEFINE_INLINE_TRACE() {}
+  DECLARE_TRACE();
 
  private:
   CSSParserContext(const KURL& baseURL,
@@ -101,7 +100,7 @@ class CORE_EXPORT CSSParserContext
                    bool isHTMLDocument,
                    bool useLegacyBackgroundSizeShorthandBehavior,
                    ContentSecurityPolicyDisposition,
-                   UseCounter*);
+                   const Document* useCounterDocument);
 
   KURL m_baseURL;
   String m_charset;
@@ -113,7 +112,7 @@ class CORE_EXPORT CSSParserContext
   bool m_useLegacyBackgroundSizeShorthandBehavior;
   ContentSecurityPolicyDisposition m_shouldCheckContentSecurityPolicy;
 
-  UseCounter* m_useCounter;
+  WeakMember<const Document> m_useCounterDocument;

[haraken, 2017/02/08 01:40:00]

Does this need to be weak? In other words, can CSSParserContext outlive the
Document?

If no, we should just use a Member.

[haraken, 2017/02/08 01:40:00]

Also I'd rename m_useCounterDocument to m_document, since it's just a document
associated with the CSSParserContext.

[Bret, 2017/02/09 01:53:33]

Rename done.

I believe it has to be a WeakMember. I originally made it a Member and
CSSLazyParsingTest.ChangeDocuments failed because m_cachedContents was holding
onto the CSSParserContext handle, which caused the Document to not be collected,
which caused CSSLazyParsingState's weak Document handle to still be valid, which
caused it to not refresh it from m_owningContents, which caused the
isDocumentHandleEqual call to return true, which caused it to use the old
UseCounter instance. Maybe something there can be simplified but I don't have
enough knowledge to know where.

[haraken, 2017/02/09 02:01:42]

Yeah, I think we should look into what's going on there and clean up.

This CL LGTM though.

 };
 
 CORE_EXPORT const CSSParserContext* strictCSSParserContext();