Appease jschuh@ by adding a setting to move 'plugin' to blockable mixed content.

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 218 matching lines @@
     // Spatial navigation feature, when enabled, improves the experience
     // of keyboard-controlling the web pages which originally were not designed
     // for keyboard navigation. It allows to use arrow keys to move focus between
     // the adjacent HTML elements. As a side effect, it extends the criteria for
     // elements to be focusable to include any element which has click or keyboard
     // event handlers specified. User can also trigger click handlers for such
     // elements using SPACE or ENTER keys.
     virtual void setSpatialNavigationEnabled(bool) = 0;
     virtual void setStandardFontFamily(const WebString&, UScriptCode = USCRIPT_COMMON) = 0;
     virtual void setStrictMixedContentChecking(bool) = 0;
+    virtual void setStrictMixedContentCheckingForPlugin(bool) = 0;
     virtual void setStrictPowerfulFeatureRestrictions(bool) = 0;
     virtual void setStrictlyBlockBlockableMixedContent(bool) = 0;
     virtual void setSupportDeprecatedTargetDensityDPI(bool) = 0;
     virtual void setSupportsMultipleWindows(bool) = 0;
     virtual void setSyncXHRInDocumentsEnabled(bool) = 0;
     virtual void setTextAreasAreResizable(bool) = 0;
     virtual void setTextAutosizingEnabled(bool) = 0;
     virtual void setAccessibilityFontScaleFactor(float) = 0;
     virtual void setTextTrackKindUserPreference(TextTrackKindUserPreference) = 0;
     virtual void setTextTrackBackgroundColor(const WebString&) = 0;
@@ skipping 27 matching lines @@
     virtual void setWideViewportQuirkEnabled(bool) = 0;
     virtual void setXSSAuditorEnabled(bool) = 0;
 
 protected:
     ~WebSettings() { }
 };
 
 } // namespace blink
 
 #endif