--- a/devtools/client/netmonitor/request-utils.js
+++ b/devtools/client/netmonitor/request-utils.js
@@ -172,14 +172,15 @@ const LOAD_CAUSE_STRINGS = {
   [Ci.nsIContentPolicy.TYPE_FONT]: "font",
   [Ci.nsIContentPolicy.TYPE_MEDIA]: "media",
   [Ci.nsIContentPolicy.TYPE_WEBSOCKET]: "websocket",
   [Ci.nsIContentPolicy.TYPE_CSP_REPORT]: "csp",
   [Ci.nsIContentPolicy.TYPE_XSLT]: "xslt",
   [Ci.nsIContentPolicy.TYPE_BEACON]: "beacon",
   [Ci.nsIContentPolicy.TYPE_FETCH]: "fetch",
   [Ci.nsIContentPolicy.TYPE_IMAGESET]: "imageset",
-  [Ci.nsIContentPolicy.TYPE_WEB_MANIFEST]: "webManifest"
+  [Ci.nsIContentPolicy.TYPE_WEB_MANIFEST]: "webManifest",
+  [Ci.nsIContentPolicy.TYPE_PREFETCH]: "prefetch",
 };
 
 exports.loadCauseString = function (causeType) {
   return LOAD_CAUSE_STRINGS[causeType] || "unknown";
 };

--- a/dom/base/nsContentPolicyUtils.h
+++ b/dom/base/nsContentPolicyUtils.h
@@ -129,16 +129,17 @@ NS_CP_ContentTypeName(uint32_t contentTy
     CASE_RETURN( TYPE_INTERNAL_EVENTSOURCE        );
     CASE_RETURN( TYPE_INTERNAL_SERVICE_WORKER     );
     CASE_RETURN( TYPE_INTERNAL_SCRIPT_PRELOAD     );
     CASE_RETURN( TYPE_INTERNAL_IMAGE              );
     CASE_RETURN( TYPE_INTERNAL_IMAGE_PRELOAD      );
     CASE_RETURN( TYPE_INTERNAL_IMAGE_FAVICON      );
     CASE_RETURN( TYPE_INTERNAL_STYLESHEET         );
     CASE_RETURN( TYPE_INTERNAL_STYLESHEET_PRELOAD );
+    CASE_RETURN( TYPE_PREFETCH                    );
    default:
     return "<Unknown Type>";
   }
 }
 
 #undef CASE_RETURN
 
 /* Passes on parameters from its "caller"'s context. */

--- a/dom/base/nsIContentPolicyBase.idl
+++ b/dom/base/nsIContentPolicyBase.idl
@@ -324,16 +324,21 @@ interface nsIContentPolicyBase : nsISupp
   /**
    * Indicates an internal constant for favicon.
    *
    * This will be mapped to TYPE_IMAGE before being passed
    * to content policy implementations.
    */
   const nsContentPolicyType TYPE_INTERNAL_IMAGE_FAVICON = 41;
 
+  /**
+   * Indicates a prefetch request (from <link rel=prefetch> or network predictor)
+   */
+  const nsContentPolicyType TYPE_PREFETCH = 42;
+
   /* When adding new content types, please update nsContentBlocker,
    * NS_CP_ContentTypeName, nsCSPContext, all nsIContentPolicy
    * implementations, the static_assert in dom/cache/DBSchema.cpp,
    * and other things that are not listed here that are related to
    * nsIContentPolicy. */
 
   //////////////////////////////////////////////////////////////////////
 

--- a/dom/cache/DBSchema.cpp
+++ b/dom/cache/DBSchema.cpp
@@ -288,17 +288,18 @@ static_assert(nsIContentPolicy::TYPE_INV
               nsIContentPolicy::TYPE_INTERNAL_XMLHTTPREQUEST == 33 &&
               nsIContentPolicy::TYPE_INTERNAL_EVENTSOURCE == 34 &&
               nsIContentPolicy::TYPE_INTERNAL_SERVICE_WORKER == 35 &&
               nsIContentPolicy::TYPE_INTERNAL_SCRIPT_PRELOAD == 36 &&
               nsIContentPolicy::TYPE_INTERNAL_IMAGE == 37 &&
               nsIContentPolicy::TYPE_INTERNAL_IMAGE_PRELOAD == 38 &&
               nsIContentPolicy::TYPE_INTERNAL_STYLESHEET == 39 &&
               nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD == 40 &&
-              nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON == 41,
+              nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON == 41 &&
+              nsIContentPolicy::TYPE_PREFETCH == 42,
               "nsContentPolicyType values are as expected");
 
 namespace {
 
 typedef int32_t EntryId;
 
 struct IdCount
 {

--- a/dom/fetch/InternalRequest.cpp
+++ b/dom/fetch/InternalRequest.cpp
@@ -252,16 +252,19 @@ InternalRequest::MapContentPolicyTypeToR
     context = RequestContext::Fetch;
     break;
   case nsIContentPolicy::TYPE_IMAGESET:
     context = RequestContext::Imageset;
     break;
   case nsIContentPolicy::TYPE_WEB_MANIFEST:
     context = RequestContext::Manifest;
     break;
+  case nsIContentPolicy::TYPE_PREFETCH:
+    context = RequestContext::Prefetch;
+    break;
   default:
     MOZ_ASSERT(false, "Unhandled nsContentPolicyType value");
     break;
   }
   return context;
 }
 
 // static

--- a/dom/fetch/InternalRequest.h
+++ b/dom/fetch/InternalRequest.h
@@ -49,32 +49,31 @@ namespace dom {
  * imageset          | TYPE_IMAGESET
  * import            | Not supported by Gecko
  * internal          | TYPE_DOCUMENT, TYPE_XBL, TYPE_OTHER
  * location          |
  * manifest          | TYPE_WEB_MANIFEST
  * object            | TYPE_INTERNAL_OBJECT
  * ping              | TYPE_PING
  * plugin            | TYPE_OBJECT_SUBREQUEST
- * prefetch          |
+ * prefetch          | TYPE_PREFETCH
  * script            | TYPE_INTERNAL_SCRIPT, TYPE_INTERNAL_SCRIPT_PRELOAD
  * sharedworker      | TYPE_INTERNAL_SHARED_WORKER
  * subresource       | Not supported by Gecko
  * style             | TYPE_INTERNAL_STYLESHEET, TYPE_INTERNAL_STYLESHEET_PRELOAD
  * track             | TYPE_INTERNAL_TRACK
  * video             | TYPE_INTERNAL_VIDEO
  * worker            | TYPE_INTERNAL_WORKER
  * xmlhttprequest    | TYPE_INTERNAL_XMLHTTPREQUEST
  * eventsource       | TYPE_INTERNAL_EVENTSOURCE
  * xslt              | TYPE_XSLT
  *
  * TODO: Figure out if TYPE_REFRESH maps to anything useful
  * TODO: Figure out if TYPE_DTD maps to anything useful
  * TODO: Figure out if TYPE_WEBSOCKET maps to anything useful
- * TODO: Add a content type for prefetch
  * TODO: Use the content type for manifest when it becomes available
  * TODO: Add a content type for location
  * TODO: Add a content type for hyperlink
  * TODO: Add a content type for form
  * TODO: Add a content type for favicon
  * TODO: Add a content type for download
  */
 

--- a/dom/security/nsContentSecurityManager.cpp
+++ b/dom/security/nsContentSecurityManager.cpp
@@ -360,16 +360,22 @@ DoContentSecurityChecks(nsIChannel* aCha
     }
 
     case nsIContentPolicy::TYPE_WEB_MANIFEST: {
       mimeTypeGuess = NS_LITERAL_CSTRING("application/manifest+json");
       requestingContext = aLoadInfo->LoadingNode();
       break;
     }
 
+    case nsIContentPolicy::TYPE_PREFETCH: {
+      mimeTypeGuess = EmptyCString();
+      requestingContext = aLoadInfo->LoadingNode();
+      break;
+    }
+
     default:
       // nsIContentPolicy::TYPE_INVALID
       MOZ_ASSERT(false, "can not perform security check without a valid contentType");
   }
 
   int16_t shouldLoad = nsIContentPolicy::ACCEPT;
   rv = NS_CheckContentLoadPolicy(internalContentPolicyType,
                                  uri,

--- a/dom/security/nsMixedContentBlocker.cpp
+++ b/dom/security/nsMixedContentBlocker.cpp
@@ -509,16 +509,17 @@ nsMixedContentBlocker::ShouldLoad(bool a
     case TYPE_FETCH:
     case TYPE_FONT:
     case TYPE_IMAGESET:
     case TYPE_OBJECT:
     case TYPE_SCRIPT:
     case TYPE_STYLESHEET:
     case TYPE_SUBDOCUMENT:
     case TYPE_PING:
+    case TYPE_PREFETCH:
     case TYPE_WEB_MANIFEST:
     case TYPE_XBL:
     case TYPE_XMLHTTPREQUEST:
     case TYPE_XSLT:
     case TYPE_OTHER:
       break;
 
 

--- a/extensions/permissions/nsContentBlocker.cpp
+++ b/extensions/permissions/nsContentBlocker.cpp
@@ -54,16 +54,23 @@ static const char *kTypeString[] = {
                                     "", // TYPE_INTERNAL_FRAME
                                     "", // TYPE_INTERNAL_IFRAME
                                     "", // TYPE_INTERNAL_AUDIO
                                     "", // TYPE_INTERNAL_VIDEO
                                     "", // TYPE_INTERNAL_TRACK
                                     "", // TYPE_INTERNAL_XMLHTTPREQUEST
                                     "", // TYPE_INTERNAL_EVENTSOURCE
                                     "", // TYPE_INTERNAL_SERVICE_WORKER
+                                    "", // TYPE_INTERNAL_SCRIPT_PRELOAD
+                                    "", // TYPE_INTERNAL_IMAGE
+                                    "", // TYPE_INTERNAL_IMAGE_PRELOAD
+                                    "", // TYPE_INTERNAL_STYLESHEET
+                                    "", // TYPE_INTERNAL_STYLESHEET_PRELOAD
+                                    "", // TYPE_INTERNAL_IMAGE_FAVICON
+                                    "prefetch",
 };
 
 #define NUMBER_OF_TYPES MOZ_ARRAY_LENGTH(kTypeString)
 uint8_t nsContentBlocker::mBehaviorPref[NUMBER_OF_TYPES];
 
 NS_IMPL_ISUPPORTS(nsContentBlocker, 
                   nsIContentPolicy,
                   nsIObserver,

--- a/netwerk/base/Predictor.cpp
+++ b/netwerk/base/Predictor.cpp
@@ -1285,17 +1285,17 @@ Predictor::Prefetch(nsIURI *uri, nsIURI 
   uri->GetAsciiSpec(strUri);
   referrer->GetAsciiSpec(strReferrer);
   PREDICTOR_LOG(("Predictor::Prefetch uri=%s referrer=%s verifier=%p",
                  strUri.get(), strReferrer.get(), verifier));
   nsCOMPtr<nsIChannel> channel;
   nsresult rv = NS_NewChannel(getter_AddRefs(channel), uri,
                               nsContentUtils::GetSystemPrincipal(),
                               nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL,
-                              nsIContentPolicy::TYPE_OTHER,
+                              nsIContentPolicy::TYPE_PREFETCH,
                               nullptr, /* aLoadGroup */
                               nullptr, /* aCallbacks */
                               nsIRequest::LOAD_BACKGROUND);
 
   if (NS_FAILED(rv)) {
     PREDICTOR_LOG(("    NS_NewChannel failed rv=0x%X", rv));
     return rv;
   }

--- a/uriloader/prefetch/nsPrefetchService.cpp
+++ b/uriloader/prefetch/nsPrefetchService.cpp
@@ -132,17 +132,17 @@ nsPrefetchNode::OpenChannel()
       }
     }
     nsresult rv = NS_NewChannelInternal(getter_AddRefs(mChannel),
                                         mURI,
                                         source,
                                         source->NodePrincipal(),
                                         nullptr,   //aTriggeringPrincipal
                                         securityFlags,
-                                        nsIContentPolicy::TYPE_OTHER,
+                                        nsIContentPolicy::TYPE_PREFETCH,
                                         loadGroup, // aLoadGroup
                                         this,      // aCallbacks
                                         nsIRequest::LOAD_BACKGROUND |
                                         nsICachingChannel::LOAD_ONLY_IF_MODIFIED);
 
     NS_ENSURE_SUCCESS(rv, rv);
 
     // configure HTTP specific stuff