Remove unused variables.

media/renderers/default_renderer_factory.cc

Index: media/renderers/default_renderer_factory.cc
diff --git a/media/renderers/default_renderer_factory.cc b/media/renderers/default_renderer_factory.cc
index 0a65a550596c7de5a144620a2133ded1cb933ba4..f5198ae0d9da2408d7bcee9ea903852b11a882c7 100644
--- a/media/renderers/default_renderer_factory.cc
+++ b/media/renderers/default_renderer_factory.cc
@@ -72,15 +72,14 @@ ScopedVector<VideoDecoder> DefaultRendererFactory::CreateVideoDecoders(
   // Create our video decoders and renderer.
   ScopedVector<VideoDecoder> video_decoders;
 
-  // |gpu_factories_| requires that its entry points be called on its
-  // |GetTaskRunner()|.  Since |pipeline_| will own decoders created from the
-  // factories, require that their message loops are identical.
-  DCHECK(!gpu_factories ||
-         (gpu_factories->GetTaskRunner() == media_task_runner.get()));
-
   // Prefer an external decoder since one will only exist if it is hardware
   // accelerated.
   if (gpu_factories) {
+    // |gpu_factories_| requires that its entry points be called on its
+    // |GetTaskRunner()|.  Since |pipeline_| will own decoders created from the
+    // factories, require that their message loops are identical.
+    DCHECK(gpu_factories->GetTaskRunner() == media_task_runner.get());
+
     if (decoder_factory_) {
       decoder_factory_->CreateVideoDecoders(media_task_runner, gpu_factories,
                                             &video_decoders);