Use WebRenderingStats::Enumerate to populate benchmarking extension renderingStats() fields.

content/common/gpu/gpu_rendering_stats.h

Index: content/common/gpu/gpu_rendering_stats.h
diff --git a/content/common/gpu/gpu_rendering_stats.h b/content/common/gpu/gpu_rendering_stats.h
index e7cad9160439626ba8d05f71e964d1be06cf4539..c2b919155b19dbb70566128a64df6de862d6c4af 100644
--- a/content/common/gpu/gpu_rendering_stats.h
+++ b/content/common/gpu/gpu_rendering_stats.h
@@ -20,6 +20,30 @@ struct CONTENT_EXPORT GpuRenderingStats {
   base::TimeDelta total_texture_upload_time;
   base::TimeDelta global_total_processing_commands_time;
   base::TimeDelta total_processing_commands_time;
+
+  // In conjunction with enumerateFields, this allows the embedder to
+  // enumerate the values in this structure without
+  // having to embed references to its specific member variables. This
+  // simplifies the addition of new fields to this type.
+  class Enumerator {
+   public:
+    virtual void addInt(const char* name, int value) = 0;
+    virtual void addTimeDelta(const char* name, base::TimeDelta value) = 0;
+   protected:
+    virtual ~Enumerator() { }
+  };
+
+  // Outputs the fields in this structure to the provided enumerator.
+  void enumerateFields(Enumerator* enumerator) const {
+    enumerator->addInt("globalTextureUploadCount", global_texture_upload_count);
+    enumerator->addTimeDelta("totalTextureUploadTime",
+                             total_texture_upload_time);
+    enumerator->addInt("textureUploadCount", texture_upload_count);
+    enumerator->addTimeDelta("globalTotalProcessingCommandsTime",
+                             global_total_processing_commands_time);
+    enumerator->addTimeDelta("totalProcessingCommandsTime",
+                             total_processing_commands_time);
+  }
 };
 
 }  // namespace content