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/RpcTransportTipcAndroid.cpp b/libs/binder/RpcTransportTipcAndroid.cpp
index cf0360f..0c81d83 100644
--- a/libs/binder/RpcTransportTipcAndroid.cpp
+++ b/libs/binder/RpcTransportTipcAndroid.cpp
@@ -26,7 +26,6 @@
 #include "RpcState.h"
 #include "RpcTransportUtils.h"
 
-using namespace android::binder::impl;
 using android::base::Error;
 using android::base::Result;
 
@@ -76,7 +75,7 @@
 
     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 {
         auto writeFn = [&](iovec* iovs, size_t niovs) -> ssize_t {
@@ -94,7 +93,7 @@
 
     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 readFn = [&](iovec* iovs, size_t niovs) -> ssize_t {