Make CSSParserContext be garbage collected.

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

 // 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.
 
 #include "core/css/ActiveStyleSheets.h"
 
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/MediaQueryEvaluator.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/StyleSheetList.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/dom/shadow/ShadowRootInit.h"
 #include "core/frame/FrameView.h"
 #include "core/html/HTMLElement.h"
 #include "core/testing/DummyPageHolder.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
 class ActiveStyleSheetsTest : public ::testing::Test {
  protected:
   static CSSStyleSheet* createSheet(const String& cssText = String()) {
     StyleSheetContents* contents =
-        StyleSheetContents::create(CSSParserContext(HTMLStandardMode, nullptr));
+        StyleSheetContents::create(CSSParserContext::create(HTMLStandardMode));
     contents->parseString(cssText);
     contents->ensureRuleSet(MediaQueryEvaluator(),
                             RuleHasDocumentSecurityOrigin);
     return CSSStyleSheet::create(contents);
   }
 };
 
 class ApplyRulesetsTest : public ActiveStyleSheetsTest {
  protected:
   void SetUp() override {
@@ skipping 423 matching lines @@
   ActiveStyleSheetVector oldStyleSheets;
   oldStyleSheets.push_back(
       std::make_pair(cssSheet, &cssSheet->contents()->ruleSet()));
   styleEngine().applyRuleSetChanges(shadowRoot, oldStyleSheets,
                                     ActiveStyleSheetVector());
 
   EXPECT_TRUE(styleEngine().treeBoundaryCrossingScopes().isEmpty());
 }
 
 }  // namespace blink