Whitelist library name metadata for slow report traces

Change-Id: I3b964533485b61c598c8ae8e515a0dc18ecd9399
Reviewed-on: https://chromium-review.googlesource.com/1049267Reviewed-by: oysteine <oysteine@chromium.org>
Commit-Queue: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556942}

chrome/common/trace_event_args_whitelist.cc

@@ -36,6 +36,7 @@ const WhitelistEntry kEventArgsWhitelist[] = {
     {nullptr, nullptr, nullptr}};
 
 const char* kMetadataWhitelist[] = {
+  "chrome-library-name",
   "clock-domain",
   "config",
   "cpu-*",