gpu: Make the log of texture binding failure more specific.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index efd75ddd0081741c099049faddac70ac6049f957..b0377a8fd0342b0026d268f1251ba1d403a201dd 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -6427,12 +6427,17 @@ bool GLES2DecoderImpl::PrepareTexturesForRender() {
           glBindTexture(
               textarget,
               texture_manager()->black_texture_id(uniform_info->type));
-          LOCAL_RENDER_WARNING(
-              std::string("texture bound to texture unit ") +
-              base::IntToString(texture_unit_index) +
-              " is not renderable. It maybe non-power-of-2 and have"
-              " incompatible texture filtering or is not"
-              " 'texture complete'");
+          if (!texture_ref) {
+            LOCAL_RENDER_WARNING(
+                std::string("there is no texture bound to the unit ") +
+                base::IntToString(texture_unit_index));
+          } else {
+            LOCAL_RENDER_WARNING(
+                std::string("texture bound to texture unit ") +
+                base::IntToString(texture_unit_index) +
+                " is not renderable. It maybe non-power-of-2 and have"
+                " incompatible texture filtering.");
+          }
           continue;
         }