gpu: Fix crash in gpu tracer

gpu/command_buffer/service/gpu_tracer.cc

Index: gpu/command_buffer/service/gpu_tracer.cc
diff --git a/gpu/command_buffer/service/gpu_tracer.cc b/gpu/command_buffer/service/gpu_tracer.cc
index aa85a88fe0c78a98da85f465891a96c1c4aa7c29..8905ee5f3be53522e5e735eb2d4f1e1e2c361995 100644
--- a/gpu/command_buffer/service/gpu_tracer.cc
+++ b/gpu/command_buffer/service/gpu_tracer.cc
@@ -271,6 +271,10 @@ bool GPUTracer::Begin(const std::string& category, const std::string& name,
   // Push new marker from given 'source'
   markers_[source].push_back(TraceMarker(category, name));
 
+  if (!outputter_) {
+    outputter_ = CreateOutputter(gpu_timing_client_->GetTimerTypeName());
+  }
+
   // Create trace
   if (IsTracing()) {
     began_device_traces_ |= (*gpu_trace_dev_category != 0);