Use a new Supplement constructor for Supplement<Document> (Part 1)

third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 28 matching lines @@
 #include "core/frame/LocalFrame.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/style/StyleRareNonInheritedData.h"
 
 namespace blink {
 
 // The address of this string is important; its value is just documentation.
 static const char kSupplementName[] = "CSSSelectorWatch";
 
 CSSSelectorWatch::CSSSelectorWatch(Document& document)
-    : m_document(document),
+    : Supplement<Document>(document),
       m_callbackSelectorChangeTimer(
           TaskRunnerHelper::get(TaskType::UnspecedTimer, &document),
           this,
           &CSSSelectorWatch::callbackSelectorChangeTimerFired),
       m_timerExpirations(0) {}
 
 CSSSelectorWatch& CSSSelectorWatch::from(Document& document) {
   CSSSelectorWatch* watch = fromIfExists(document);
   if (!watch) {
     watch = new CSSSelectorWatch(document);
     Supplement<Document>::provideTo(document, kSupplementName, watch);
   }
   return *watch;
 }
 
 CSSSelectorWatch* CSSSelectorWatch::fromIfExists(Document& document) {
   return static_cast<CSSSelectorWatch*>(
       Supplement<Document>::from(document, kSupplementName));
 }
 
 void CSSSelectorWatch::callbackSelectorChangeTimerFired(TimerBase*) {
   // Should be ensured by updateSelectorMatches():
   DCHECK(!m_addedSelectors.isEmpty() || !m_removedSelectors.isEmpty());
 
   if (m_timerExpirations < 1) {
     m_timerExpirations++;
     m_callbackSelectorChangeTimer.startOneShot(0, BLINK_FROM_HERE);
     return;
   }
-  if (document().frame()) {
+  if (host()->frame()) {

[sof, 2017/01/06 07:55:06]

passing comment/thought - might there be a more self-explanatory naming of the
supplementable's |host()| ?

     Vector<String> addedSelectors;
     Vector<String> removedSelectors;
     copyToVector(m_addedSelectors, addedSelectors);
     copyToVector(m_removedSelectors, removedSelectors);
-    document().frame()->loader().client()->selectorMatchChanged(
-        addedSelectors, removedSelectors);
+    host()->frame()->loader().client()->selectorMatchChanged(addedSelectors,
+                                                             removedSelectors);
   }
   m_addedSelectors.clear();
   m_removedSelectors.clear();
   m_timerExpirations = 0;
 }
 
 void CSSSelectorWatch::updateSelectorMatches(
     const Vector<String>& removedSelectors,
     const Vector<String>& addedSelectors) {
   bool shouldUpdateTimer = false;
@@ skipping 61 matching lines @@
     if (!selectorList.isValid())
       continue;
 
     // Only accept Compound Selectors, since they're cheaper to match.
     if (!allCompound(selectorList))
       continue;
 
     m_watchedCallbackSelectors.push_back(
         StyleRule::create(std::move(selectorList), callbackPropertySet));
   }
-  document().styleEngine().watchedSelectorsChanged();
+  host()->styleEngine().watchedSelectorsChanged();
 }
 
 DEFINE_TRACE(CSSSelectorWatch) {
   visitor->trace(m_watchedCallbackSelectors);
-  visitor->trace(m_document);
   Supplement<Document>::trace(visitor);
 }
 
 }  // namespace blink