Add GL_EXT_color_buffer_half_float support

gpu/command_buffer/service/context_group.cc

Index: gpu/command_buffer/service/context_group.cc
diff --git a/gpu/command_buffer/service/context_group.cc b/gpu/command_buffer/service/context_group.cc
index 3bb365ad1496b55ef0beca28e552d325443874be..6c078a45c2294f58aeb3353694f72a45a582ce91 100644
--- a/gpu/command_buffer/service/context_group.cc
+++ b/gpu/command_buffer/service/context_group.cc
@@ -50,6 +50,7 @@ DisallowedFeatures AdjustDisallowedFeatures(
     adjusted_disallowed_features.chromium_color_buffer_float_rgba = true;
     adjusted_disallowed_features.chromium_color_buffer_float_rgb = true;
     adjusted_disallowed_features.ext_color_buffer_float = true;
+    adjusted_disallowed_features.ext_color_buffer_half_float = true;
     adjusted_disallowed_features.oes_texture_float_linear = true;
   }
   return adjusted_disallowed_features;