Add 'XHR' to the Resource::Type enum, and use it for XHR requests.

Source/core/fetch/ResourceLoaderOptions.h

Index: Source/core/fetch/ResourceLoaderOptions.h
diff --git a/Source/core/fetch/ResourceLoaderOptions.h b/Source/core/fetch/ResourceLoaderOptions.h
index baa01e455a4a35230f7daf1d7eeac9ca01a8da7f..9139554287eb701ee34c8e56c8a2f95673fb7436 100644
--- a/Source/core/fetch/ResourceLoaderOptions.h
+++ b/Source/core/fetch/ResourceLoaderOptions.h
@@ -70,13 +70,6 @@ enum CredentialRequest {
     ClientDidNotRequestCredentials
 };
 
-enum MixedContentBlockingTreatment {
-    TreatAsDefaultForType,
-    TreatAsPassiveContent,
-    TreatAsActiveContent,
-    TreatAsAlwaysAllowedContent
-};
-
 enum SynchronousPolicy {
     RequestSynchronously,
     RequestAsynchronously
@@ -97,7 +90,6 @@ struct ResourceLoaderOptions {
         , credentialsRequested(ClientDidNotRequestCredentials)
         , contentSecurityPolicyOption(CheckContentSecurityPolicy)
         , requestInitiatorContext(DocumentContext)
-        , mixedContentBlockingTreatment(TreatAsDefaultForType)
         , synchronousPolicy(RequestAsynchronously)
         , corsEnabled(NotCORSEnabled)
     {
@@ -116,7 +108,6 @@ struct ResourceLoaderOptions {
         , credentialsRequested(credentialsRequested)
         , contentSecurityPolicyOption(contentSecurityPolicyOption)
         , requestInitiatorContext(requestInitiatorContext)
-        , mixedContentBlockingTreatment(TreatAsDefaultForType)
         , synchronousPolicy(RequestAsynchronously)
         , corsEnabled(NotCORSEnabled)
     {
@@ -134,7 +125,6 @@ struct ResourceLoaderOptions {
         // FIXME: check contentSecurityPolicyOption.
         // initiatorInfo is purely informational and should be benign for re-use.
         // requestInitiatorContext is benign (indicates document vs. worker)
-        // FIXME: check mixedContentBlockingTreatment.
         // synchronousPolicy (safe to re-use an async XHR response for sync, etc.)
         return corsEnabled == other.corsEnabled;
         // securityOrigin has more complicated checks which callers are responsible for.
@@ -147,7 +137,6 @@ struct ResourceLoaderOptions {
     ContentSecurityPolicyCheck contentSecurityPolicyOption;
     FetchInitiatorInfo initiatorInfo;
     RequestInitiatorContext requestInitiatorContext;
-    MixedContentBlockingTreatment mixedContentBlockingTreatment;
     SynchronousPolicy synchronousPolicy;
     CORSEnabled corsEnabled; // If the resource is loaded out-of-origin, whether or not to use CORS.
     RefPtr<SecurityOrigin> securityOrigin;