gpu_messages.h => gpu/ipc/common

This cl moves gpu_messages.h and associated dependencies
all to gpu/ipc/common.

It turns out that NaCl depends on gpu/ipc/common, and we
cannot link skia into NaCl and so I split up gpu/ipc/common
into two source_sets in GN and two gypis on GYP:
command_buffer_traits and ipc_common_sources (GN) /
gpu_ipc_common (GYP).

The parts that NaCl needs live in command_buffer_traits and
that's what NaCl depends on.

Other dependencies that moved are:

gpu_param_traits.cc
gpu_param_traits.h
gpu_param_traits_macros.h
gpu_stream_constants.h

BUG=595721
CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel

Review URL: https://codereview.chromium.org/1809183002

Cr-Commit-Position: refs/heads/master@{#382514}
diff --git a/content/gpu/BUILD.gn b/content/gpu/BUILD.gn
index 0d685c73..ff076ea 100644
--- a/content/gpu/BUILD.gn
+++ b/content/gpu/BUILD.gn
@@ -51,7 +51,7 @@
     "//content/public/child:child_sources",
     "//content/public/common:common_sources",
     "//gpu:gpu",
-    "//gpu/ipc/common",
+    "//gpu/ipc/common:command_buffer_traits",
     "//ipc",
     "//mojo/shell/public/interfaces",
     "//skia",