Tests active mixed content blocking in the security panel.
<DIV class=security-explanation security-explanation-info >
<DEVTOOLS-ICON role=presentation name=info class=security-property security-property-info >
<#document-fragment >
<SPAN style=--icon-url: var(--image-file-info); >
</SPAN>
<STYLE >
</STYLE>
</#document-fragment>
</DEVTOOLS-ICON>
<DIV class=security-explanation-text >
<DIV class=security-explanation-title >
Blocked mixed content
</DIV>
<DIV >
Your page requested non-secure resources that were blocked.
</DIV>
<BUTTON class=security-mixed-content devtools-link text-button link-style role=link tabindex=0 >
View 1 request in Network Panel
</BUTTON>
</DIV>
</DIV>