Dev tools warning and console warning for document.write script blocking

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

Index: third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
index f09d2ece98f445c40de0f3ebdabb3a5295bc29b7..b3bcee216e63ab69093a9f512e711f177b77d3b6 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
@@ -80,7 +80,14 @@ namespace blink {
 
 namespace {
 
-bool shouldDisallowFetchForMainFrameScript(const ResourceRequest& request, FetchRequest::DeferOption defer, const Document& document)
+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 shouldDisallowFetchForMainFrameScript(const ResourceRequest& request, FetchRequest::DeferOption defer, Document& document)
 {
     // Only scripts inserted via document.write are candidates for having their
     // fetch disallowed.
@@ -106,6 +113,8 @@ bool shouldDisallowFetchForMainFrameScript(const ResourceRequest& request, Fetch
     if (request.url().host() == document.getSecurityOrigin()->domain())
         return false;
 
+    emitWarningForDocWriteScripts(request.url().getString(), document);
+
     // Do not block scripts if it is a page reload. This is to enable pages to
     // recover if blocking of a script is leading to a page break and the user
     // reloads the page.