Add unittest to avoid duplicate id in gpu driver bug list

gpu/config/gpu_control_list.h

Index: gpu/config/gpu_control_list.h
diff --git a/gpu/config/gpu_control_list.h b/gpu/config/gpu_control_list.h
index 8fc373f7b1dc6cc4e9336e7a335e905029c06ea8..944d3f5e4705e682658fab8e186225048e2ffe2b 100644
--- a/gpu/config/gpu_control_list.h
+++ b/gpu/config/gpu_control_list.h
@@ -91,6 +91,9 @@ class GPU_EXPORT GpuControlList {
   // Returns the number of entries.  This is only for tests.
   size_t num_entries() const;
 
+  // This is only for tests.
+  bool has_duplicated_entry_id() const;
+
   // Register a feature to FeatureMap - used to construct a GpuControlList.
   void AddSupportedFeature(const std::string& feature_name, int feature_id);
   // Register whether "all" is recognized as all features.