base::RefCounted now DCHECKs when referenced from multiple threads.

gpu/command_buffer/service/shader_translator_cache.h

 // 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.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_SHADER_TRANSLATOR_CACHE_H_
 #define GPU_COMMAND_BUFFER_SERVICE_SHADER_TRANSLATOR_CACHE_H_
 
 #include <string.h>
 
 #include <map>
 
 #include "base/memory/ref_counted.h"
 #include "gpu/command_buffer/service/shader_translator.h"
 #include "third_party/angle/include/GLSLANG/ShaderLang.h"
 
 namespace gpu {
 namespace gles2 {
 
 // This class is not thread safe and can only be created and destroyed
 // on a single thread. But it is safe to use two independent instances on two
 // threads without synchronization.
 //
 // TODO(backer): Investigate using glReleaseShaderCompiler as an alternative to
 // to this cache.
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
 class GPU_EXPORT ShaderTranslatorCache
-    : public base::RefCounted<ShaderTranslatorCache>,
+    : public base::UnsafeRefCounted<ShaderTranslatorCache>,
       public NON_EXPORTED_BASE(ShaderTranslator::DestructionObserver) {
  public:
   ShaderTranslatorCache();
 
   // ShaderTranslator::DestructionObserver implementation
   void OnDestruct(ShaderTranslator* translator) override;
 
   scoped_refptr<ShaderTranslator> GetTranslator(
       sh::GLenum shader_type,
       ShShaderSpec shader_spec,
       const ShBuiltInResources* resources,
       ShaderTranslatorInterface::GlslImplementationType
           glsl_implementation_type,
       ShCompileOptions driver_bug_workarounds);
 
  private:
-  friend class base::RefCounted<ShaderTranslatorCache>;
+  friend class base::UnsafeRefCounted<ShaderTranslatorCache>;
   friend class ShaderTranslatorCacheTest_InitParamComparable_Test;
   ~ShaderTranslatorCache() override;
 
   // Parameters passed into ShaderTranslator::Init
   struct ShaderTranslatorInitParams {
     sh::GLenum shader_type;
     ShShaderSpec shader_spec;
     ShBuiltInResources resources;
     ShaderTranslatorInterface::GlslImplementationType
         glsl_implementation_type;
@@ skipping 33 matching lines @@
   typedef std::map<ShaderTranslatorInitParams, ShaderTranslator* > Cache;
   Cache cache_;
 
   DISALLOW_COPY_AND_ASSIGN(ShaderTranslatorCache);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_SHADER_TRANSLATOR_CACHE_H_