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

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 8c0ac57d4bf95c606086bb514f7a2ff2de5e106a..d043c62a259b3b8b10adc4aa3bbbfd89f5ba4285 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1068,6 +1068,9 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
   settings->setStrictlyBlockBlockableMixedContent(
       prefs.strictly_block_blockable_mixed_content);
 
+  settings->setStrictMixedContentCheckingForPlugin(
+      prefs.block_mixed_plugin_content);
+
   settings->setStrictPowerfulFeatureRestrictions(
       prefs.strict_powerful_feature_restrictions);
   settings->setPasswordEchoEnabled(prefs.password_echo_enabled);