Add GPU events to slow-reports whitelist

This CL is adding the GPU events to the whitelist.

We do not accept any args yet, since some of them may contains PII and
are not yet useful to investigate GPU issues. We will update the
|kGPUAllowedArgs| array when needed. For now, let assume no args.

R=oysteine@chromium.org

Bug: 888580
Change-Id: Ia23ba1c0e2ed6a49328416678062074ffab472a6
Reviewed-on: https://chromium-review.googlesource.com/1249914Reviewed-by: oysteine <oysteine@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594856}

chrome/common/trace_event_args_whitelist.cc

@@ -18,6 +18,7 @@ struct WhitelistEntry {
   const char* const* arg_name_filter;
 };
 
+const char* const kGPUAllowedArgs[] = {nullptr};
 const char* const kInputLatencyAllowedArgs[] = {"data", nullptr};
 const char* const kMemoryDumpAllowedArgs[] = {"dumps", nullptr};
 
@@ -29,6 +30,7 @@ const WhitelistEntry kEventArgsWhitelist[] = {
     {"__metadata", "chrome_library_module", nullptr},
     {"__metadata", "stackFrames", nullptr},
     {"__metadata", "typeNames", nullptr},
+    {"GPU", "*", kGPUAllowedArgs},
     {"ipc", "GpuChannelHost::Send", nullptr},
     {"ipc", "SyncChannel::Send", nullptr},
     {"latencyInfo", "*", kInputLatencyAllowedArgs},