[DocWriteBlocking] Add feature to block doc.written scripts if 2g-like network

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 71 matching lines @@
 
 namespace {
 
 void emitWarningForDocWriteScripts(const String& url, Document& document)
 {
     String message = "A Parser-blocking, cross-origin script, " + url + ", is invoked via document.write. This may be blocked by the browser if the device has poor network connectivity.";
     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;
+    case WebEffectiveConnectionType::Type3G:
+    case WebEffectiveConnectionType::Type4G:
+    case WebEffectiveConnectionType::TypeUnknown:
+    case WebEffectiveConnectionType::TypeOffline:
+        return false;
+    }
+    NOTREACHED();
+    return false;
+}
+
 bool shouldDisallowFetchForMainFrameScript(const ResourceRequest& request, FetchRequest::DeferOption defer, Document& document)
 {
     // Only scripts inserted via document.write are candidates for having their
     // fetch disallowed.
     if (!document.isInDocumentWrite())
         return false;
 
     if (!document.settings())
         return false;
 
@@ skipping 37 matching lines @@
         // where a script was blocked could be indicative of a page break.
         document.loader()->didObserveLoadingBehavior(WebLoadingBehaviorFlag::WebLoadingBehaviorDocumentWriteBlockReload);
         return false;
     }
 
     // Add the metadata that this page has scripts inserted via document.write
     // that are eligible for blocking. Note that if there are multiple scripts
     // the flag will be conveyed to the browser process only once.
     document.loader()->didObserveLoadingBehavior(WebLoadingBehaviorFlag::WebLoadingBehaviorDocumentWriteBlock);
 
-    const bool isSlowConnection = networkStateNotifier().connectionType() == WebConnectionTypeCellular2G;
-    const bool disallowFetch = document.settings()->disallowFetchForDocWrittenScriptsInMainFrame() || (document.settings()->disallowFetchForDocWrittenScriptsInMainFrameOnSlowConnections() && isSlowConnection);
+    const bool is2G = networkStateNotifier().connectionType() == WebConnectionTypeCellular2G;
+    WebEffectiveConnectionType effectiveConnection = document.frame()->loader().client()->getEffectiveConnectionType();
+    const bool is2GOrLike2G = is2G || isConnectionEffectively2G(effectiveConnection);
 
-    return disallowFetch;
+    return document.settings()->disallowFetchForDocWrittenScriptsInMainFrame() || (document.settings()->disallowFetchForDocWrittenScriptsInMainFrameOnSlowConnections() && is2G) || (RuntimeEnabledFeatures::blockDocWriteIfEffectively2GEnabled() && is2GOrLike2G);
 }
 
 } // namespace
 
 FrameFetchContext::FrameFetchContext(DocumentLoader* loader, Document* document)
     : m_document(document)
     , m_documentLoader(loader)
 {
     ASSERT(frame());
 }
@@ skipping 666 matching lines @@
 }
 
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
     visitor->trace(m_documentLoader);
     FetchContext::trace(visitor);
 }
 
 } // namespace blink