Fix crash caused by concurrent access to framebuffer_combo_complete_map_.

gpu/command_buffer/service/framebuffer_completeness_cache.h

Index: gpu/command_buffer/service/framebuffer_completeness_cache.h
diff --git a/gpu/command_buffer/service/framebuffer_completeness_cache.h b/gpu/command_buffer/service/framebuffer_completeness_cache.h
new file mode 100644
index 0000000000000000000000000000000000000000..7200cbdea66d7c1ea832f79c322f0dda9104f214
--- /dev/null
+++ b/gpu/command_buffer/service/framebuffer_completeness_cache.h
@@ -0,0 +1,42 @@
+// Copyright 2015 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_FRAMEBUFFER_COMPLETENESS_CACHE_H_
+#define GPU_COMMAND_BUFFER_SERVICE_FRAMEBUFFER_COMPLETENESS_CACHE_H_
+
+#include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
+#include "gpu/gpu_export.h"
+
+namespace gpu {
+namespace gles2 {
+
+// Refcounted wrapper for a hash_set of framebuffer format signatures
+// representing framebuffer configurations that are reported by the GL
+// driver as complete according to glCheckFramebufferStatusEXT.
+class GPU_EXPORT FramebufferCompletenessCache
+    : public base::RefCounted<FramebufferCompletenessCache> {
+ public:
+  FramebufferCompletenessCache();
+
+  bool IsComplete(const std::string& signature) const;
+  void SetComplete(const std::string& signature);
+
+ protected:
+  virtual ~FramebufferCompletenessCache();
+
+ private:
+  friend class base::RefCounted<FramebufferCompletenessCache>;
+
+  typedef base::hash_set<std::string> Map;
+
+  Map cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(FramebufferCompletenessCache);
+};
+
+}  // namespace gles2
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_FRAMEBUFFER_COMPLETENESS_CACHE_H_