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

Source/core/loader/MixedContentChecker.cpp

Index: Source/core/loader/MixedContentChecker.cpp
diff --git a/Source/core/loader/MixedContentChecker.cpp b/Source/core/loader/MixedContentChecker.cpp
index c130d131a6d0f55791e34edf1feee5309d827fa1..449058f80cec9b82bb8e0a250f6ee313b3b95c8c 100644
--- a/Source/core/loader/MixedContentChecker.cpp
+++ b/Source/core/loader/MixedContentChecker.cpp
@@ -99,17 +99,22 @@ LocalFrame* MixedContentChecker::inWhichFrameIsContentMixed(LocalFrame* frame, W
 }
 
 // static
-MixedContentChecker::ContextType MixedContentChecker::contextTypeFromContext(WebURLRequest::RequestContext context)
+MixedContentChecker::ContextType MixedContentChecker::contextTypeFromContext(WebURLRequest::RequestContext context, LocalFrame* frame)
 {
     switch (context) {
     // "Optionally-blockable" mixed content
     case WebURLRequest::RequestContextAudio:
     case WebURLRequest::RequestContextFavicon:
     case WebURLRequest::RequestContextImage:
-    case WebURLRequest::RequestContextPlugin:
     case WebURLRequest::RequestContextVideo:
         return ContextTypeOptionallyBlockable;
 
+    // Plugins! Oh how dearly we love plugin-loaded content!
+    case WebURLRequest::RequestContextPlugin: {
+        Settings* settings = frame->settings();
+        return settings || settings->strictMixedContentCheckingForPlugin() ? ContextTypeBlockable : ContextTypeOptionallyBlockable;
+    }
+
     // "Blockable" mixed content
     case WebURLRequest::RequestContextBeacon:
     case WebURLRequest::RequestContextCSPReport:
@@ -246,7 +251,7 @@ void MixedContentChecker::count(LocalFrame* frame, WebURLRequest::RequestContext
 
     // Roll blockable content up into a single counter, count unblocked types individually so we
     // can determine when they can be safely moved to the blockable category:
-    ContextType contextType = contextTypeFromContext(requestContext);
+    ContextType contextType = contextTypeFromContext(requestContext, frame);
     if (contextType == ContextTypeBlockable) {
         UseCounter::count(frame, UseCounter::MixedContentBlockable);
         return;
@@ -304,7 +309,7 @@ bool MixedContentChecker::shouldBlockFetch(LocalFrame* frame, WebURLRequest::Req
     // the client checks in order to prevent degrading the site's security UI.
     bool strictMode = mixedFrame->document()->shouldEnforceStrictMixedContentChecking() || settings->strictMixedContentChecking();
 
-    ContextType contextType = contextTypeFromContext(requestContext);
+    ContextType contextType = contextTypeFromContext(requestContext, mixedFrame);
 
     // If we're loading the main resource of a subframe, we need to take a close look at the loaded URL.
     // If we're dealing with a CORS-enabled scheme, then block mixed frames as active content. Otherwise,