Refactor content/common/gpu into gpu/ipc/service. This is a part of a larger refactor for Mus (see label:gpurefactor).

BUG=586385
CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel

Committed: https://crrev.com/721be995e023023793e547c28e0f6f7843bdbd99
Cr-Commit-Position: refs/heads/master@{#384705}

Review URL: https://codereview.chromium.org/1845563005

Cr-Commit-Position: refs/heads/master@{#386084}

diff --git a/BUILD.gn b/BUILD.gn
index cb6edd7..fa73308 100644
--- a/BUILD.gn
+++ b/BUILD.gn

@@ -175,6 +175,7 @@
       "//content/test:content_unittests",
       "//device:device_unittests",
       "//gpu:gpu_unittests",
+      "//gpu/ipc/service:gpu_ipc_service_unittests",
       "//ipc:ipc_tests",
       "//ipc/mojo:ipc_mojo_unittests",
       "//media:media_unittests",