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

third_party/WebKit/Source/core/css/StyleSheetContents.cpp

Index: third_party/WebKit/Source/core/css/StyleSheetContents.cpp
diff --git a/third_party/WebKit/Source/core/css/StyleSheetContents.cpp b/third_party/WebKit/Source/core/css/StyleSheetContents.cpp
index 0e38ceab3898dbcb56d8971f303a46bbb436d259..ff289ed16b0cb378ed89c0c3f5a6698cf51746b6 100644
--- a/third_party/WebKit/Source/core/css/StyleSheetContents.cpp
+++ b/third_party/WebKit/Source/core/css/StyleSheetContents.cpp
@@ -39,6 +39,16 @@
 
 namespace blink {
 
+// static
+const Document* StyleSheetContents::singleOwnerDocument(
+    const StyleSheetContents* styleSheetContents) {
+  // FIXME(https://crbug.com/242125): We may want to handle stylesheets that

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

TODO

[Bret, 2017/02/09 02:08:18]

Done.

+  // have multiple owners when this is used for UseCounter.
+  if (styleSheetContents && styleSheetContents->hasSingleOwnerNode())
+    return styleSheetContents->singleOwnerDocument();
+  return nullptr;
+}
+
 // Rough size estimate for the memory cache.
 unsigned StyleSheetContents::estimatedSizeInBytes() const {
   // Note that this does not take into account size of the strings hanging from