gpu: Add UMA statistic for RG texture support.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index dcbdb8fbf37a99c59db6bd812895dde8e0156f8b..bcd9b69d313dd31e9ae99c62e49293911068e23b 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -1088,6 +1088,7 @@ void FeatureInfo::InitializeFeatures() {
       texture_format_validators_[GL_RG_EXT].AddValue(GL_HALF_FLOAT_OES);
     }
   }
+  UMA_HISTOGRAM_BOOLEAN("GPU.TextureRG", feature_flags_.ext_texture_rg);
 
 #if !defined(OS_MACOSX)
   if (workarounds_.ignore_egl_sync_failures) {