Doc.write intervention warning and error messages fixed for clarity.

third_party/WebKit/Source/core/loader/FrameFetchContext.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 73 matching lines @@
 #include <memory>
 
 namespace blink {
 
 namespace {
 
 void emitWarningForDocWriteScripts(const String& url, Document& document) {
   String message =
       "A Parser-blocking, cross site (i.e. different eTLD+1) script, " + url +
       ", is invoked via document.write. This may be blocked by "
-      "the browser if the device has poor network connectivity. "
+      "the browser due to poor network connectivity. "
       "See https://www.chromestatus.com/feature/5718547946799104 "
-      "for more details.";
+      "for more details. If the script is indeed blocked, you should see an "

[Bryan McQuade, 2017/01/18 23:47:04]

thinking about this more i'm a little concerned that devs might interpret this
last sentence as "if i don't see the subsequent error, my page isn't affected by
this issue" and they won't fix their page, so I'm inclined to omit this last "If
the script is indeed blocked..." text. We can make it clear in the linked
documentation that this message is a warning and only if you see the additional
'script was blocked' message was there an actual issue.

Given this, can we remove this last sentence?

[shivanisha, 2017/01/19 18:04:58]

I hear your concern. Omitting the last sentence might still leave users unsure
whether it actually was blocked or not, in case they do not read the link very
carefully. How about something like this:

"A Parser-blocking, cross site (i.e. different eTLD+1) script
http://ajax.cloudflare.com/cdn-cgi/nexp/dok3v=f2befc48d1/cloudflare.min.js, is
invoked via document.write. This MAY be blocked by the browser in this or a
future page load due to poor network connectivity. If blocked in this page load,
it will be confirmed in a subsequent ERROR message. See
https://www.chromestatus.com/feature/5718547946799104 for more details."

+      "error message following this.";
   document.addConsoleMessage(
       ConsoleMessage::create(JSMessageSource, WarningMessageLevel, message));
   WTFLogAlways("%s", message.utf8().data());
 }
 
 bool isConnectionEffectively2G(WebEffectiveConnectionType effectiveType) {
   switch (effectiveType) {
     case WebEffectiveConnectionType::TypeSlow2G:
     case WebEffectiveConnectionType::Type2G:
       return true;
@@ skipping 968 matching lines @@
                                                     response);
 }
 
 DEFINE_TRACE(FrameFetchContext) {
   visitor->trace(m_document);
   visitor->trace(m_documentLoader);
   FetchContext::trace(visitor);
 }
 
 }  // namespace blink