Add a setting to strictly block "blockable" mixed content.

Source/core/loader/MixedContentChecker.cpp

 /*
  * Copyright (C) 2012 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
@@ skipping 305 matching lines @@
         contextType = ContextTypeOptionallyBlockable;
 
     switch (contextType) {
     case ContextTypeOptionallyBlockable:
         allowed = !strictMode && client->allowDisplayingInsecureContent(settings && settings->allowDisplayOfInsecureContent(), securityOrigin, url);
         if (allowed)
             client->didDisplayInsecureContent();
         break;
 
     case ContextTypeBlockable:
-        allowed = !strictMode && client->allowRunningInsecureContent(settings && settings->allowRunningOfInsecureContent(), securityOrigin, url);
+        allowed = !strictMode && !settings->strictlyBlockBlockableMixedContent() && client->allowRunningInsecureContent(settings && settings->allowRunningOfInsecureContent(), securityOrigin, url);
         if (allowed) {
             client->didRunInsecureContent(securityOrigin, url);
             UseCounter::count(mixedFrame, UseCounter::MixedContentBlockableAllowed);
         }
         break;
 
     case ContextTypeShouldBeBlockable:
         allowed = !strictMode;
         if (allowed)
             client->didDisplayInsecureContent();
@@ skipping 77 matching lines @@
 {
     if (!frame || !frame->document() || !frame->document()->loader())
         return;
 
     // Just count these for the moment, don't block them.
     if (Platform::current()->isReservedIPAddress(resourceIPAddress) && !frame->document()->isHostedInReservedIPRange())
         UseCounter::count(frame->document(), UseCounter::MixedContentPrivateHostnameInPublicHostname);
 }
 
 } // namespace blink