Bug 1482129 - Exempt stylesheets, fonts and images when canceling loading of slow HTTP requests of tracking resources; r=valentin

dom/base/nsIContentPolicy.idl

@@ -348,10 +348,11 @@ interface nsIContentPolicy : nsISupports
 
   /* When adding new content types, please update nsContentBlocker,
    * NS_CP_ContentTypeName, nsCSPContext, CSP_ContentTypeToDirective,
-   * DoContentSecurityChecks, all nsIContentPolicy implementations, the
-   * static_assert in dom/cache/DBSchema.cpp, ChannelWrapper.webidl,
-   * ChannelWrapper.cpp, nsPermissionManager.cpp, and other things that are not
-   * listed here that are related to nsIContentPolicy. */
+   * DoContentSecurityChecks, IsContentPolicyTypeWhitelistedForFastBlock,
+   * all nsIContentPolicy implementations, the static_assert in
+   * dom/cache/DBSchema.cpp, ChannelWrapper.webidl, ChannelWrapper.cpp,
+   * nsPermissionManager.cpp, and other things that are not listed here
+   * that are related to nsIContentPolicy. */
 
   //////////////////////////////////////////////////////////////////////
 

netwerk/protocol/http/nsHttpChannel.cpp

@@ -596,6 +596,31 @@ nsHttpChannel::Connect()
     return ConnectOnTailUnblock();
 }
 
+static bool
+IsContentPolicyTypeWhitelistedForFastBlock(nsILoadInfo* aLoadInfo)
+{
+  nsContentPolicyType type = aLoadInfo ?
+                             aLoadInfo->GetExternalContentPolicyType() :
+                             nsIContentPolicy::TYPE_OTHER;
+  switch (type) {
+  // images
+  case nsIContentPolicy::TYPE_IMAGE:
+  case nsIContentPolicy::TYPE_IMAGESET:
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE:
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE_PRELOAD:
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON:
+  // fonts
+  case nsIContentPolicy::TYPE_FONT:
+  // stylesheets
+  case nsIContentPolicy::TYPE_STYLESHEET:
+  case nsIContentPolicy::TYPE_INTERNAL_STYLESHEET:
+  case nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD:
+    return true;
+  default:
+    return false;
+  }
+}
+
 bool
 nsHttpChannel::CheckFastBlocked()
 {
@@ -616,7 +641,9 @@ nsHttpChannel::CheckFastBlocked()
         return false;
     }
 
-    if (!sIsFastBlockEnabled || !timestamp) {
+    if (!sIsFastBlockEnabled ||
+        IsContentPolicyTypeWhitelistedForFastBlock(mLoadInfo) ||
+        !timestamp) {
         return false;
     }