Revert "Use std::function instead of base::function_ref"

Revert submission 2780893

Reason for revert: breaking boot tests

Bug: 308214260

Reverted changes: /q/submissionid:2780893

Change-Id: Ibbd9bf2c9eb1389c9b8217cc75a98a3ec13b77d8
diff --git a/libs/binder/RpcTransportRaw.cpp b/libs/binder/RpcTransportRaw.cpp
index ffa3151..c089811 100644
--- a/libs/binder/RpcTransportRaw.cpp
+++ b/libs/binder/RpcTransportRaw.cpp
@@ -29,8 +29,6 @@
 
 namespace android {
 
-using namespace android::binder::impl;
-
 // RpcTransport with TLS disabled.
 class RpcTransportRaw : public RpcTransport {
 public:
@@ -56,7 +54,7 @@
 
     status_t interruptableWriteFully(
             FdTrigger* fdTrigger, iovec* iovs, int niovs,
-            const std::optional<SmallFunction<status_t()>>& altPoll,
+            const std::optional<android::base::function_ref<status_t()>>& altPoll,
             const std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds)
             override {
         bool sentFds = false;
@@ -72,7 +70,7 @@
 
     status_t interruptableReadFully(
             FdTrigger* fdTrigger, iovec* iovs, int niovs,
-            const std::optional<SmallFunction<status_t()>>& altPoll,
+            const std::optional<android::base::function_ref<status_t()>>& altPoll,
             std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds) override {
         auto recv = [&](iovec* iovs, int niovs) -> ssize_t {
             return binder::os::receiveMessageFromSocket(mSocket, iovs, niovs, ancillaryFds);