Revert of Implement WTF::WeakPtr in terms of base::WeakPtr

third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp

Index: third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
index 0a9187b1cb9175fb0a4352f7eaaea695aa665815..3002ac9ad7bfc93d64a921b431914a13f54c6383 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
@@ -761,6 +761,9 @@
     if (document()->loader())
         document()->ensureStyleResolver();
 
+    RefPtr<WeakReference<BackgroundHTMLParser>> reference = WeakReference<BackgroundHTMLParser>::createUnbound();
+    m_backgroundParser = WeakPtr<BackgroundHTMLParser>(reference);
+
     std::unique_ptr<BackgroundHTMLParser::Configuration> config = wrapUnique(new BackgroundHTMLParser::Configuration);
     config->options = m_options;
     config->parser = m_weakFactory.createWeakPtr();
@@ -778,15 +781,15 @@
     }
 
     ASSERT(config->xssAuditor->isSafeToSendToAnotherThread());
-
-    // The background parser is created on the main thread, but may otherwise
-    // only be used from the parser thread.
-    m_backgroundParser = BackgroundHTMLParser::create(
-        std::move(config),
-        m_loadingTaskRunner->clone());
-    // TODO(csharrison): This is a hack to initialize MediaValuesCached on the
-    // correct thread. We should get rid of it.
-    postTaskToLookaheadParser(Synchronous, &BackgroundHTMLParser::init, m_backgroundParser, document()->url(), passed(CachedDocumentParameters::create(document())), MediaValuesCached::MediaValuesCachedData(*document()));
+    postTaskToLookaheadParser(
+        Synchronous,
+        &BackgroundHTMLParser::start,
+        reference.release(),
+        passed(std::move(config)),
+        document()->url(),
+        passed(CachedDocumentParameters::create(document())),
+        MediaValuesCached::MediaValuesCachedData(*document()),
+        passed(m_loadingTaskRunner->clone()));
 }
 
 void HTMLDocumentParser::stopBackgroundParser()