Making the warning message more clear and adding an error message when the script actually gets blo…

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

 /*
  * Copyright (C) 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 21 matching lines @@
 #include "core/dom/Element.h"
 #include "core/dom/IgnoreDestructiveWriteCountIncrementer.h"
 #include "core/dom/ScriptLoader.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "core/events/Event.h"
 #include "core/fetch/MemoryCache.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/parser/HTMLInputStream.h"
 #include "core/html/parser/HTMLParserScriptRunnerHost.h"
 #include "core/html/parser/NestingLevelIncrementer.h"
+#include "core/inspector/ConsoleMessage.h"
 #include "core/loader/resource/ScriptResource.h"
 #include "platform/Histogram.h"
 #include "platform/WebFrameScheduler.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/instrumentation/tracing/TracedValue.h"
 #include "public/platform/Platform.h"
 #include <inttypes.h>
 #include <memory>
 
 namespace blink {
@@ skipping 201 matching lines @@
                                 const TextPosition& scriptStartPosition) {
   DCHECK(script);
 
   ScriptLoader* scriptLoader =
       ScriptLoader::create(script, isParserInserted, false, false);
   DCHECK(scriptLoader);
   scriptLoader->setFetchDocWrittenScriptDeferIdle();
   scriptLoader->prepareScript(scriptStartPosition);
 }
 
+void emitWarningForDocWriteScripts(const String& url, Document& document) {
+  String message =
+      "The Parser-blocking, cross site (i.e. different eTLD+1) "
+      "script, " +
+      url +
+      ", invoked via document.write was NOT BLOCKED on this page load, but MAY "
+      "be blocked by the browser in future page loads with poor network "
+      "connectivity.";
+  document.addConsoleMessage(
+      ConsoleMessage::create(JSMessageSource, WarningMessageLevel, message));
+  WTFLogAlways("%s", message.utf8().data());
+}
+
+void emitErrorForDocWriteScripts(const String& url, Document& document) {
+  String message =
+      "The Parser-blocking, cross site (i.e. different eTLD+1) "
+      "script, " +
+      url +
+      ", invoked via document.write was BLOCKED by the browser due to poor "
+      "network connectivity. ";
+  document.addConsoleMessage(
+      ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
+  WTFLogAlways("%s", message.utf8().data());
+}
+
 void HTMLParserScriptRunner::possiblyFetchBlockedDocWriteScript(
     PendingScript* pendingScript) {
   // If the script was blocked as part of document.write intervention,
   // then send an asynchronous GET request with an interventions header.
-  Element* element = nullptr;
   TextPosition startingPosition;
   bool isParserInserted = false;
 
-  if (!pendingScript->errorOccurred() ||
-      m_parserBlockingScript != pendingScript)
+  if (m_parserBlockingScript != pendingScript)
     return;
 
+  Element* element = m_parserBlockingScript->element();
+  if (!element)
+    return;
+
+  ScriptLoader* scriptLoader = toScriptLoaderIfPossible(element);
+  if (!scriptLoader || !scriptLoader->disallowedFetchForDocWrittenScript())
+    return;
+
+  if (!pendingScript->errorOccurred()) {
+    emitWarningForDocWriteScripts(pendingScript->resource()->url().getString(),
+                                  *m_document);
+    return;
+  }
+
   // Due to dependency violation, not able to check the exact error to be
   // ERR_CACHE_MISS but other errors are rare with
   // WebCachePolicy::ReturnCacheDataDontLoad.
-  element = m_parserBlockingScript->element();
 
-  ScriptLoader* scriptLoader = nullptr;
-  if (element && (scriptLoader = toScriptLoaderIfPossible(element)) &&
-      scriptLoader->disallowedFetchForDocWrittenScript()) {
-    startingPosition = m_parserBlockingScript->startingPosition();
-    isParserInserted = scriptLoader->isParserInserted();
-    // remove this resource entry from memory cache as the new request
-    // should not join onto this existing entry.
-    memoryCache()->remove(pendingScript->resource());
-    fetchBlockedDocWriteScript(element, isParserInserted, startingPosition);
-  }
+  emitErrorForDocWriteScripts(pendingScript->resource()->url().getString(),
+                              *m_document);
+  startingPosition = m_parserBlockingScript->startingPosition();
+  isParserInserted = scriptLoader->isParserInserted();
+  // Remove this resource entry from memory cache as the new request
+  // should not join onto this existing entry.
+  memoryCache()->remove(pendingScript->resource());
+  fetchBlockedDocWriteScript(element, isParserInserted, startingPosition);
 }
 
 void HTMLParserScriptRunner::pendingScriptFinished(
     PendingScript* pendingScript) {
   // Handle cancellations of parser-blocking script loads without
   // notifying the host (i.e., parser) if these were initiated by nested
   // document.write()s. The cancellation may have been triggered by
   // script execution to signal an abrupt stop (e.g., window.close().)
   //
   // The parser is unprepared to be told, and doesn't need to be.
@@ skipping 215 matching lines @@
 
 DEFINE_TRACE(HTMLParserScriptRunner) {
   visitor->trace(m_document);
   visitor->trace(m_host);
   visitor->trace(m_parserBlockingScript);
   visitor->trace(m_scriptsToExecuteAfterParsing);
   PendingScriptClient::trace(visitor);
 }
 
 }  // namespace blink