Fix crash in //content/browser/font_access/

Fix potential crash found by the
"bugprone-use-after-move" clang-tidy check.

Bug: 1122844
Change-Id: Iba1093736fa49775ad0c3605bc78e0a65cb890d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2431487Reviewed-by: Olivier Yiptong <oyiptong@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811487}

content/browser/font_access/font_access_manager_impl.cc

@@ -50,6 +50,7 @@ void FontAccessManagerImpl::EnumerateLocalFonts(
     std::move(callback).Run(
         blink::mojom::FontEnumerationStatus::kUnexpectedError,
         base::ReadOnlySharedMemoryRegion());
+    return;
   }
 
   // Sticky User Activation is required for the API to function at all.