Pure pedantry: Replace all ".size() == 0" with ".empty()".

o3d/core/cross/gl/effect_gl.cc

Index: o3d/core/cross/gl/effect_gl.cc
diff --git a/o3d/core/cross/gl/effect_gl.cc b/o3d/core/cross/gl/effect_gl.cc
index 71ce60228ff2e01d9aadf894eb01e9a7c0bd418d..755d80ada743761a68eb0c8f4570e2fee6dde4fe 100644
--- a/o3d/core/cross/gl/effect_gl.cc
+++ b/o3d/core/cross/gl/effect_gl.cc
@@ -378,7 +378,7 @@ ParamTexture* EffectGL::GetTextureParamFromCgSampler(
   DLOG_ASSERT(cgGetParameterType(cg_sampler) != CG_SAMPLER);
   String sampler_name = cgGetParameterName(cg_sampler);
   String param_name = GetTextureNameFromSamplerParamName(sampler_name);
-  if (param_name.size() == 0) {
+  if (param_name.empty()) {
     // Sampler has no texture associated with it.
     return NULL;
   }