GN: Create a :gles2_interface target to resolve some check errors in //cc.

gpu/command_buffer/client/BUILD.gn

 # Copyright (c) 2013 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.
 
 source_set("client") {
   sources = [
     "cmd_buffer_helper.cc",
     "cmd_buffer_helper.h",
     "fenced_allocator.cc",
     "fenced_allocator.h",
@@ skipping 59 matching lines @@
   "buffer_tracker.h",
   "client_context_state.h",
   "client_context_state.cc",
   "client_context_state_autogen.h",
   "client_context_state_impl_autogen.h",
   "gles2_impl_export.h",
   "gles2_implementation_autogen.h",
   "gles2_implementation.cc",
   "gles2_implementation.h",
   "gles2_implementation_impl_autogen.h",
-  "gles2_interface.h",
   "gles2_trace_implementation_autogen.h",
   "gles2_trace_implementation.cc",
   "gles2_trace_implementation.h",
   "gles2_trace_implementation_impl_autogen.h",
   "gpu_memory_buffer_factory.h",
   "gpu_memory_buffer_tracker.cc",
   "gpu_memory_buffer_tracker.h",
   "program_info_manager.cc",
   "program_info_manager.h",
   "query_tracker.cc",
   "query_tracker.h",
   "share_group.cc",
   "share_group.h",
   "vertex_array_object_manager.cc",
   "vertex_array_object_manager.h",
 ]
 
+# Provides GLES2 interface, but does not cause any implementation to be linked
+# in. Useful when a target uses the interface, but permits its users to choose
+# an implementation.
+source_set("gles2_interface") {
+  sources = [ "gles2_interface.h" ]
+  direct_dependent_configs = [ "//third_party/khronos:khronos_headers" ]
+  deps = [
+    "//base",
+  ]
+}
+
 # Library emulates GLES2 using command_buffers.
 component("gles2_implementation") {
   sources = gles2_implementation_source_files
 
   defines = [ "GLES2_IMPL_IMPLEMENTATION" ]
   all_dependent_configs = [ "//third_party/khronos:khronos_headers" ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]  # size_t to int truncation.
   }
 
   deps = [
     ":gles2_cmd_helper",
+    ":gles2_interface",
     "//base",
     "//gpu/command_buffer/common",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 }
 
 # Library emulates GLES2 using command_buffers.
 component("gles2_implementation_client_side_arrays") {
   sources = gles2_implementation_source_files
 
   defines = [
     "GLES2_IMPL_IMPLEMENTATION",
     "GLES2_SUPPORT_CLIENT_SIDE_ARRAYS=1",
   ]
   all_dependent_configs = [ "//third_party/khronos:khronos_headers" ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]  # size_t to int truncation.
   }
 
   deps = [
     ":gles2_cmd_helper",
+    ":gles2_interface",
     "//base",
     "//gpu/command_buffer/common",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 }
 
 component("gl_in_process_context") {
   sources = [
     "gl_in_process_context.h",
@@ skipping 18 matching lines @@
   sources = gles2_c_lib_source_files
   defines = [ "GLES2_C_LIB_IMPLEMENTATION" ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]  # size_t to int truncation.
   }
 
   deps = [
     ":client",
+    ":gles2_interface",
     "//base",
     "//base/third_party/dynamic_annotations",
     "//gpu/command_buffer/common",
   ]
 }