Bug 1587385 - Give a better info (not error) message if a webfont is not used because of font-display timeout. r=heycam

This is not an error in the same way as a download failure, and should not be reported as one.
An Info message is sufficient.

Also suppress "unknown" location in messages about @font-face rules, as it is not useful,
pending a proper fix (bug 1450903).

Differential Revision: https://phabricator.services.mozilla.com/D50346

--HG--
extra : moz-landing-system : lando

gfx/thebes/gfxUserFontSet.cpp

@@ -899,12 +899,14 @@ void gfxUserFontEntry::FontDataDownloadComplete(
     return;
   }
 
-  // download failed
-  mFontSet->LogMessage(
-      this,
-      (mFontDataLoadingState != LOADING_TIMED_OUT ? "download failed"
-                                                  : "download timed out"),
-      nsIScriptError::errorFlag, aDownloadStatus);
+  // download failed or font-display timeout passed
+  if (mFontDataLoadingState == LOADING_TIMED_OUT) {
+    mFontSet->LogMessage(this, "font-display timeout, webfont not used",
+                         nsIScriptError::infoFlag, aDownloadStatus);
+  } else {
+    mFontSet->LogMessage(this, "download failed", nsIScriptError::errorFlag,
+                         aDownloadStatus);
+  }
 
   if (aFontData) {
     free((void*)aFontData);

layout/style/FontFaceSet.cpp

@@ -1270,7 +1270,7 @@ nsresult FontFaceSet::LogMessage(gfxUserFontEntry* aUserFontEntry,
       href.AssignLiteral("unknown");
     }
 #endif
-    href.AssignLiteral("unknown");
+    // Leave href empty if we don't know how to get the correct sheet.
   }
 
   nsresult rv;