Convert some GN test support targets to static libs.

gpu/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GYP-to-GN project mappings:
 #
 #  gpu.gyp:command_buffer_client => //gpu/command_buffer/client
 #
 #  gpu.gyp:command_buffer_common => //gpu/command_buffer/common
 #
@@ skipping 109 matching lines @@
 
   if (is_android) {
     libs += [ "android" ]
     deps += [ "//ui/android:ui_java" ]
   }
   if (is_linux && !is_component_build) {
     configs += [ "//build/config/gcc:rpath_for_built_shared_libraries" ]
   }
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "command_buffer/client/gles2_interface_stub.cc",
     "command_buffer/client/gles2_interface_stub.h",
     "command_buffer/service/error_state_mock.cc",
     "command_buffer/service/gles2_cmd_decoder_mock.cc",
   ]
 
   public_deps = [
     ":gpu",
@@ skipping 257 matching lines @@
     "//testing/gtest",
     "//testing/perf",
     "//ui/gfx/geometry",
     "//ui/gl",
     "//ui/gl/init",
   ]
 
   # This target should not require the Chrome executable to run.
   assert_no_deps = [ "//chrome" ]
 }