Add glWaitSync to GPU command buffer.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index f530974de0582ed0aa9ea9b7ede3ed8020854a5e..6b254e0966bb8ad2de4ee746bf53e6f7cb3dc269 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -12087,6 +12087,24 @@ error::Error GLES2DecoderImpl::HandleClientWaitSync(
   return error::kNoError;
 }
 
+error::Error GLES2DecoderImpl::HandleWaitSync(
+    uint32_t immediate_data_size, const void* cmd_data) {
+  if (!unsafe_es3_apis_enabled())
+    return error::kUnknownCommand;
+  const gles2::cmds::WaitSync& c =
+      *static_cast<const gles2::cmds::WaitSync*>(cmd_data);
+  GLuint sync = static_cast<GLuint>(c.sync);
+  GLbitfield flags = static_cast<GLbitfield>(c.flags);
+  GLuint64 timeout = GLES2Util::MapTwoUint32ToUint64(c.timeout_0, c.timeout_1);
+  GLsync service_sync = 0;
+  if (!group_->GetSyncServiceId(sync, &service_sync)) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "WaitSync", "invalid sync");
+    return error::kNoError;
+  }
+  glWaitSync(service_sync, flags, timeout);
+  return error::kNoError;
+}
+
 void GLES2DecoderImpl::OnTextureRefDetachedFromFramebuffer(
     TextureRef* texture_ref) {
   Texture* texture = texture_ref->texture();