Check that |gpu_channel_host_| is not NULL before passing it along.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 49fbf589abe00fd20e127c6565a8632d81f7cf21..9fe3977cd1dd1ce871ef01b9eb728c83a78ec68b 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1449,6 +1449,7 @@ RenderThreadImpl::GetGpuFactories() {
     bool parsed_image_texture_target =
         base::StringToUint(image_texture_target_string, &image_texture_target);
     DCHECK(parsed_image_texture_target);
+    CHECK(gpu_channel_host.get());

[jochen (gone - plz use gerrit), 2015/07/21 14:12:58]

please add a comment pointing at the crbug, and consider printing something when
you hit the CHECK(), e.g.

CHECK(gpu_channel_host.get()) << "No gpu_channel_host?? see crbug.com/495185";

[sandersd (OOO until July 31), 2015/07/21 17:29:57]

Done.

     gpu_factories = RendererGpuVideoAcceleratorFactories::Create(
         gpu_channel_host.get(), media_task_runner, gpu_va_context_provider_,
         image_texture_target, enable_video_accelerator);