ui: Add libsync GLFence implementation.

gpu/ipc/client/BUILD.gn

Index: gpu/ipc/client/BUILD.gn
diff --git a/gpu/ipc/client/BUILD.gn b/gpu/ipc/client/BUILD.gn
index bdbfc09a8247f309602eaf54c41e0cfc933ca233..599fa49a37d5b6988315b2a2443225d444882cf1 100644
--- a/gpu/ipc/client/BUILD.gn
+++ b/gpu/ipc/client/BUILD.gn
@@ -24,6 +24,8 @@ source_set("ipc_client_sources") {
     "gpu_channel_host.h",
     "gpu_fence_impl.cc",
     "gpu_fence_impl.h",
+    "gpu_fence_impl_shared_event.cc",
+    "gpu_fence_impl_shared_event.h",
     "gpu_memory_buffer_impl.cc",
     "gpu_memory_buffer_impl.h",
     "gpu_memory_buffer_impl_shared_memory.cc",
@@ -44,6 +46,12 @@ source_set("ipc_client_sources") {
     ]
     libs = [ "android" ]
   }
+  if (is_linux) {
+    sources += [
+      "gpu_fence_impl_libsync.cc",
+      "gpu_fence_impl_libsync.h",
+    ]
+  }
   if (use_ozone) {
     sources += [
       "gpu_memory_buffer_impl_ozone_native_pixmap.cc",
@@ -71,4 +79,7 @@ source_set("ipc_client_sources") {
   if (use_ozone) {
     deps += [ "//ui/ozone" ]
   }
+  if (is_linux) {
+    deps += [ "//third_party/libsync" ]
+  }
 }