Bug 1641682. Don't kick off a validation network request if the original image network request hasn't finished. r=aosmond

Differential Revision: https://phabricator.services.mozilla.com/D78858

image/imgLoader.cpp

@@ -1929,6 +1929,29 @@ bool imgLoader::ValidateEntry(
     return false;
   }
 
+  bool requestGotLoad = false;
+  RefPtr<ProgressTracker> tracker;
+  RefPtr<Image> image = request->GetImage();
+  if (image) {
+    tracker = image->GetProgressTracker();
+  } else {
+    tracker = request->GetProgressTracker();
+  }
+  if (tracker) {
+    if ((tracker->GetProgress() & (FLAG_LOAD_COMPLETE | FLAG_HAS_ERROR)) ==
+        FLAG_LOAD_COMPLETE) {
+      requestGotLoad = true;
+    }
+  }
+  // If the original request is still transferring don't kick off a validation
+  // network request because it is a bit silly to issue a validation request if
+  // the original request hasn't even finished yet. So just return true
+  // indicating the caller can create a new proxy for the request and use it as
+  // is.
+  if (!requestGotLoad) {
+    return true;
+  }
+
   if (validateRequest && aCanMakeNewChannel) {
     LOG_SCOPE(gImgLog, "imgLoader::ValidateRequest |cache hit| must validate");