gpu: Make sure external texture destination is initialized

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 a97842748a229514d3b2d0e7c20b78911200ccf0..568f603c1e53a5273445020e3158ff77301f7e14 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -9627,7 +9627,15 @@ void GLES2DecoderImpl::DoCopyTextureCHROMIUM(
 
   // Set source texture's width and height to be the same as
   // destination texture when source is GL_TEXTURE_EXTERNAL_OES.
+  // TODO(hkuang): Add support to get width/height of StreamTexture
+  // crbug.com/225781.
   if (source_texture->target() == GL_TEXTURE_EXTERNAL_OES) {
+    if (!dest_level_defined) {
+      LOCAL_SET_GL_ERROR(
+          GL_INVALID_VALUE,
+          "glCopyTextureCHROMIUM", "destination level not defined");
+      return;
+    }
     source_width = dest_width;
     source_height = dest_height;
   }