Only destroy GPUTracer if the pointer is not empty.

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 3738 matching lines @@
   // Need to release these before releasing |group_| which may own the
   // ShaderTranslatorCache.
   fragment_translator_ = NULL;
   vertex_translator_ = NULL;
 
   // Should destroy the transfer manager before the texture manager held
   // by the context group.
   async_pixel_transfer_manager_.reset();
 
   // Destroy the GPU Tracer which may own some in process GPU Timings.
-  gpu_tracer_->Destroy(have_context);
-  gpu_tracer_ = NULL;
+  if (gpu_tracer_) {
+    gpu_tracer_->Destroy(have_context);
+    gpu_tracer_.reset();
+  }
 
   if (group_.get()) {
     framebuffer_manager()->RemoveObserver(this);
     group_->Destroy(this, have_context);
     group_ = NULL;
   }
 
   if (context_.get()) {
     context_->ReleaseCurrent(NULL);
     context_ = NULL;
@@ skipping 8667 matching lines @@
   }
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu