EstablishGpuChannel directly if in the task runner thread

This follows up:
https://chromium-review.googlesource.com/c/chromium/src/+/1125518/22/content/browser/gpu/gpu_client_impl.cc#70

BUG=857217

Change-Id: I4139661d39744bed3aab9ccdda72fc2976739472
Reviewed-on: https://chromium-review.googlesource.com/1136221
Commit-Queue: Xing Xu <xing.xu@intel.com>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575196}
1 file changed