Remove the allow-displaying-mixed-content setting from Blink.

third_party/WebKit/public/web/WebSettings.h

 /*
  * Copyright (C) 2009 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 111 matching lines @@
     virtual void setAcceleratedCompositingEnabled(bool) = 0;
     virtual void setPreferCompositingToLCDTextEnabled(bool) = 0;
     // Not implemented yet, see http://crbug.com/178119
     virtual void setAcceleratedCompositingForTransitionEnabled(bool) { }
     // If set to true, allows frames with an https origin to display passive
     // contents at an insecure URL. Otherwise, disallows it. The
     // FrameLoaderClient set to the frame may override the value set by this
     // method.
     virtual void setAccessibilityEnabled(bool) = 0;
     virtual void setAccessibilityPasswordValuesEnabled(bool) = 0;
-    virtual void setAllowDisplayOfInsecureContent(bool) = 0;
     virtual void setAllowFileAccessFromFileURLs(bool) = 0;
     virtual void setAllowCustomScrollbarInMainFrame(bool) = 0;
     virtual void setAllowGeolocationOnInsecureOrigins(bool) = 0;
     // If set to true, allows frames with an https origin to run active
     // contents at an insecure URL. This includes WebSockets. Otherwise,
     // disallows it. The FrameLoaderClient set to the frame may override the
     // value set by this method.
     virtual void setAllowRunningOfInsecureContent(bool) = 0;
     virtual void setAllowScriptsToCloseWindows(bool) = 0;
     virtual void setAllowUniversalAccessFromFileURLs(bool) = 0;
@@ skipping 134 matching lines @@
     virtual void setWideViewportQuirkEnabled(bool) = 0;
     virtual void setXSSAuditorEnabled(bool) = 0;
 
 protected:
     ~WebSettings() { }
 };
 
 } // namespace blink
 
 #endif